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## Complete Summary

#### GUIDELINE TITLE

Guidelines for the performance of the sweat test for the investigation
of cystic fibrosis in the UK.

#### BIBLIOGRAPHIC SOURCE(S)

Guidelines for the performance of the sweat test for the investigation
of cystic fibrosis in the UK. London: Royal College of Paediatrics and
Child Health; 2003 Nov 1. 97 p. \[123 references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

### COMPLETE SUMMARY CONTENT

 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

Cystic fibrosis (CF)

#### GUIDELINE CATEGORY

Diagnosis

#### CLINICAL SPECIALTY

Internal Medicine\
Pediatrics\
Pulmonary Medicine

#### INTENDED USERS

Advanced Practice Nurses\
Clinical Laboratory Personnel\
Physician Assistants\
Physicians\
Respiratory Care Practitioners

#### GUIDELINE OBJECTIVE(S)

To produce guidelines on how to perform the sweat test for the
investigation of cystic fibrosis in the United Kingdom with emphasis on:

-   Organisation/delivery for patient care (including patient/parent
    information)

-   Sweat collection (including subject suitability)

-   Sweat analysis

-   Quality of the testing

-   Interpretation of results (including false positives; indications
    for repeat analysis; use of other tests)

-   Who should do the collection and analysis

-   Assessment of competence and training needs

#### TARGET POPULATION

Children aged 0-18 years with one or more of the following indications:

-   Phenotype suggestive of cystic fibrosis (CF)

-   Family history of cystic fibrosis

-   A positive newborn screening test

-   Suspicion of an atypical phenotype

#### INTERVENTIONS AND PRACTICES CONSIDERED

**Sweat test for cystic fibrosis, including the following aspects of
testing:**

1.  Providing patient and parents with information and obtaining
    informed consent

2.  Ascertaining subject suitability

    -   Clinical state

    -   Exclusions/restrictions

3.  Sweat collection

    -   Site of collection, avoidance of contamination, and number of
        collections

    -   Stimulation methods and equipment (power supply and electrodes,
        electrolyte solutions \[e.g., pilocarpine, magnesium sulphate
        solutions\], iontophoresis time and current, safety precautions)

    -   Collection medium/time/containers

4.  Sweat analysis

    -   Weighing

    -   Elution of sweat from filter paper

    -   Analytes (chloride and sodium recommended); sweat conductivity
        (osmolality considered but not recommended)

    -   Analytical methods (calorimetry, coulometry, indirect ion
        selective electrode, direct ion selective electrode, flame
        photometry)

    -   Reporting format

5.  Quality control

    -   Internal quality control

    -   External quality assessment

    -   Audit

6.  Reference values and interpretation

    -   Definitions

    -   False positives

    -   Repeat testing

    -   Use of other tests

7.  Responsibility for testing and training

    -   Responsibility for sweat testing

    -   Who should perform sweat testing?

    -   Competence/training issues

#### MAJOR OUTCOMES CONSIDERED

-   Accuracy and precision of testing procedures for diagnosis of cystic
    fibrosis

-   Incidence of false-positive and false-negative test results

-   Safety of testing procedures

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Hand-searches of Published Literature (Primary Sources)\
Hand-searches of Published Literature (Secondary Sources)\
Searches of Electronic Databases\
Searches of Unpublished Data

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

The search process comprised the following:

-   Searching of computerised databases

    -   Medline 1965-2001

    -   Human studies

    -   Children 0-18 years

    -   All types

    -   Reviews, meta-analyses, searched on sweat tests, editorials,
        clinical trials, letters, etc.

-   Hand searching

    -   Text books and review articles

    -   Review of existing literature assembled by expert group members

    -   Selected articles pre 1965

    -   Personal contact with recognised national and international
        experts - UK, USA, Australia

-   Specific searching:

> For particular sections of the report, specific searching as detailed
> below was undertaken:
>
> **Sweat collection**

1.  Published articles on sweat test combined with:

    -   Iontophoresis

    -   Burns

    -   Urticaria

    -   Apparatus

    -   Equipment

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2.  Review of questionnaire data collected for sweat test workshops from
    30 centres (Association of Clinical Biochemists National Meeting
    1998 and UK National External Quality Assessment Schemes Workshop
    1998)

3.  Wescor instruction manuals (Webster sweat collection system
    model 3500. 1979; Macroduct sweat collection system model
    3600-sys 1983) and Website (http;//www.wescor.com)

4.  Data collected by Internet enquiry (Association of Clinical
    Biochemists Mailbase) and personal contact with colleagues in UK,
    USA, and Australia.

5.  Information supplied by Wescor, Inc., via Chemlab Scientific
    Products, Astra House, Christy Close, Southfield Business Park,
    Laindon, Essex, SS15 6TQ, in response to enquiry.

> **Sweat Analysis**

1.  Searched on Medical Subject Headings (MeSH) vocabulary for Sweat
    Test. No exact match, except for the following:

    -   Sweat

    -   Sweating

    -   Gland, Sweat

    -   Testing

    -   Searched on: Iontophoresis, burns, urticaria, equipment, and
        supplies

    -   Used a combination of MeSH and keyword or textword searching

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2.  UK National External Quality Assurance Schemes Sweat Test External
    Quality Assurance Surveys

> **Quality**

1.  UK Audits on Sweat Testing (unpublished data)

2.  UK National External Quality Assessment Schemes Data from Sweat
    External Quality Assessment Surveys

    -   Review of existing Consensus Based Guidelines

        -   National Committee for Clinical Laboratory Standards (NCCLS)
            2000

        -   Welsh Sweat Standard 1999

-   National UK Laboratory Sweat Test Subgroup

    -   This comprises evidence from a \'Consensus of experts\'
        collected from the National UK Laboratory Subgroup

    -   Under the chairmanship of Dr. J. Kirk, the subgroup was made up
        of: Birmingham Children\'s Hospital (Dr. A. Green), Edinburgh
        Royal Hospital for Sick Children (Dr. J. Kirk), Great Ormond
        Street (Dr. Tony Reynolds), Sheffield Children\'s Hospital
        (Dr. J. Bonham), Southend Hospital (Mr. M. Fahie Wilson),
        UKNEQAS (Mr. Finlay McKenzie). The group discussed data that had
        been collected by a precirculated questionnaire. Data was
        collected from the meeting participants and also from Belfast
        Sick Children\'s Hospital (Ms. G. Roberts), Bristol Children\'s
        Hospital (Dr. J. Stone), University Hospital, Cardiff (Ms H.
        Losty), Glasgow Royal Hospital for Sick Children (Mrs. M. Rae),
        St James University Hospital, Leeds (Dr. L Shapiro), Liverpool
        Children\'s Hospital (Dr. D. Isherwood) and Manchester
        Children\'s Hospital (Dr. M. Addison). Data was collected on
        site of collection, number of collections, equipment, collection
        time, minimum sweat rate, definition of upper limit of reference
        range and lower limit of CF range and methodology.

    -   The evidence base for the guidelines was updated during the
        course of the guideline development process to take account of
        newly published evidence and evidence arising from the open
        review meeting/consultation process.

#### NUMBER OF SOURCE DOCUMENTS

> Not stated

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

> Weighting According to a Rating Scheme (Scheme Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

> **Levels of Evidence**
>
> The levels of evidence are based on the U.S. Agency for Health Care
> Policy (AHCPR) 1992
>
> **I a**: Evidence obtained from meta-analysis of randomised controlled
> trials
>
> **I b**: Evidence obtained from at least one randomised controlled
> trial
>
> **II a**: Evidence obtained from at least one well designed controlled
> study without randomisation
>
> **II b**: Evidence from at least one other type of quasi-experimental
> descriptive study
>
> **III**: Evidence obtained from well designed, nonexperimental
> descriptive studies such as comparative studies, correlation studies
> and case studies
>
> **IV**: Evidence obtained from expert committee reports or opinions
> and/or clinical experience of respected authorities
>
> [Note]{.underline}: The guideline development group felt that the
> Scottish Intercollegiate Guidelines Network (SIGN) criteria,
> particularly IIb and III, are sometimes difficult to interpret in the
> context of performance of a laboratory diagnostic test. The working
> group has interpreted these levels as follows:
>
> **IIb**

-   A planned scientific study with hypothesis

-   A study not controlled

-   An experimental study, with a low risk of bias

> **III**

-   Nonexperimental/observational study

-   Investigation of a standard procedure

#### METHODS USED TO ANALYZE THE EVIDENCE

> Systematic Review

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

> The Working Group has undertaken a systematic review of evidence in
> accordance with Scottish Intercollegiate Guidelines Network (SIGN)
> methodology and the evidence and recommendations have been graded
> according to this.  The working group note that the SIGN grading
> system had been revised since work on these guidelines commenced. It
> was felt that the revised version offered no advantage in this
> instance and, therefore, after consultation with the Royal College of
> Paediatrics & Child Health, the original SIGN version has been used.
>
> Additional points of note are:

-   Publication was not considered essential to be considered as good
    evidence.

-   Where several pieces of evidence relate to the same topic, an
    \'overall evidence\' level has been assessed.

-   Because it is unethical to undertake controlled trials (randomised
    or otherwise) to evaluate variability in the performance of the
    sweat test, there are little data which qualify as grade I or grade
    II evidence.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

> Expert Consensus

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

> The Working Group was formed in October 2000 and met on 6 occasions
> throughout 2000/1/2. The process for guideline development undertaken
> by the Working Group is summarised as Figure 1 of the original
> guideline document.
>
> Formulation of recommendations was reached by consensus agreement of
> the working group members.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

> **Grading of Recommendations**
>
> The criteria for the grading of recommendations in this document are
> based upon those used by the U.S. Agency for Health Care Policy and
> Research (AHCPR), and published by the Scottish Intercollegiate
> Guidelines Network (SIGN)\*\*
>
> **A (levels I a and I b)**: Requires at least one randomised
> controlled trial as part of the body of literature of overall good
> quality and consistency addressing the specific recommendation
>
> **B (levels II a, II b, III)**: Requires availability of well
> conducted clinical studies but no randomised clinical trials on the
> topic of the recommendation
>
> **C (level IV)**: Requires evidence from expert committee reports or
> opinions and/or clinical experience of respected authorities.
> Indicates absence of directly applicable studies of good quality
>
> \*\*The working group note that the SIGN grading system had been
> revised since work on these guidelines commenced. It was felt that the
> revised version offered no advantage in this instance and, therefore,
> after consultation with the Royal College of Paediatrics & Child
> Health, the original SIGN version has been used.

#### COST ANALYSIS

> A formal cost analysis was not performed and published cost analyses
> were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

> External Peer Review\
> Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

> This guideline was issued from the Working Group in draft form in July
> 2002, and in final form in November 2003 after incorporation of
> comments from the formal appraisal by the Royal College of Paediatrics
> and Child Health.
>
> **Consultation and Peer Review**

1.  **Discussion forum**

> The first draft of the guideline was presented to the Cystic Fibrosis
> Trust Directors (September 7th September 2001) and at an open meeting
> for all professionals/patient group representatives on November 13th
> 2001 (see Appendix 3 of the original guideline document).
>
> Comments and new evidence resulting from these meetings were
> subsequently considered by the working group at a meeting on November
> 14th, 2001.

2.  **Web**

> Draft guidelines were made available on the following Web sites during
> November and December 2001 and January 2002:
>
> Association of Clinical Biochemists
>
> The Royal College of Pathologists informed members of the availability
> of the guidelines with an invitation for comment
>
> United Kingdom National External Quality Assessment Schemes (UKNEQAS)

3.  **Consultation**

> Views of interested parties not on the working group have been
> addressed by circulation of the draft guidelines to:
>
> Wescor Inc., LOGAN, Utah, U.S.A.
>
> Clinical Pathology Accreditation (UK) Ltd., 45 Rutland Park, Botanical
> Gardens, SHEFFIELD, S10 2PB
>
> UKNEQAS,P.O. Box 3909, BIRMINGHAM, B15 2UE
>
> Comments arising from this consultation period were addressed by the
> working group chairman in consultation with group members. A consensus
> agreement was reached by the group for each comment.

4.  **Specialist Independent Peer Reviewers**

> The guidelines were reviewed by a panel of independent expert peer
> reviewers. Comments were addressed by the working group at a meeting
> on February 19th, 2002 and consensus agreement reached. The draft
> guidelines were modified in response to the reviewers\' suggestions.
>
> Please refer to the original guideline document for a list of the
> names and addresses of the independent peer reviewers.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

> Levels of evidence and recommendation grades are defined at the end of
> the \"Major Recommendations\" field. An asterisk is used to note
> changes in recommendation grades following the appraisal process.

+-----------------------------------------+-------+-------------------+
| **Patient Information**                 | **Gr  | **References**    |
|                                         | ade** |                   |
+=========================================+=======+===================+
| -   It is good clinical practice to     | **C** |                   |
|     prepare the patient and, where      |       |                   |
|     appropriate, parent effectively     |       |                   |
|     before testing.                     |       |                   |
|                                         |       |                   |
| > Informed consent should be obtained   |       |                   |
| > in accordance with local policy.      |       |                   |
| >                                       |       |                   |
| > Pretest information appropriate for   |       |                   |
| > the individual should include why the |       |                   |
| > test is being done, how it will be    |       |                   |
| > performed, risks associated with the  |       |                   |
| > test, what the subject will           |       |                   |
| > experience, and contact details       |       |                   |
| > regarding the testing and final       |       |                   |
| > result. An example leaflet for        |       |                   |
| > patients/parents is provided (see     |       |                   |
| > Appendix document 1 of the original   |       |                   |
| > guideline document).                  |       |                   |
+-----------------------------------------+-------+-------------------+
| **Subject Suitability**                 |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat tests can be performed after  | **C** |                   |
|     2 weeks of age in infants greater   |       |                   |
|     than 3 kg who are normally hydrated |       |                   |
|     and without significant systemic    |       |                   |
|     illness                             |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat testing can be attempted in   | **C** |                   |
|     term infants after 7 days of age if |       |                   |
|     clinically important, but will need |       |                   |
|     repeating if insufficient quantity  |       |                   |
|     of sweat is collected.              |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat tests should be delayed in    | **C** |                   |
|     subjects who are dehydrated,        |       |                   |
|     systemically unwell or who have     |       |                   |
|     eczema affecting the potential      |       |                   |
|     stimulation sites.                  |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat tests should be delayed in    | **C** |                   |
|     subjects who are oedematous and/or  |       |                   |
|     on systemic corticosteroids.        |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat tests should not be performed | **C** |                   |
|     in subjects who are on oxygen by an |       |                   |
|     open delivery system. This would    |       |                   |
|     not apply to an infant in headbox   |       |                   |
|     or on nasal prong oxygen.           |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat tests can be performed in     | **C** | (Williams et al., |
|     subjects on flucloxacillin.         |       | 1988)             |
+-----------------------------------------+-------+-------------------+
| **Sweat Collection**                    |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The flexor surface of either        | **C** |                   |
|     forearm is the preferred site for   |       |                   |
|     sweat collection. Consideration may |       |                   |
|     be given to other sites if both     |       |                   |
|     arms are eczematous, too small or   |       |                   |
|     otherwise unsuitable. Other sites   |       |                   |
|     used successfully include the upper |       |                   |
|     arm, thigh and back.                |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Great care must be taken at all     | **C** |                   |
|     stages of the procedure to avoid    |       |                   |
|     contamination (see example standard |       |                   |
|     operating procedure \[SOP\] in the  |       |                   |
|     original guideline document).       |       |                   |
+-----------------------------------------+-------+-------------------+
| -   In response to a sweat test request | **Not | (Reynolds,        |
|     it is sufficient to carry out one   | Grade | personal          |
|     sweat collection only.              | d**\* | communication)    |
+-----------------------------------------+-------+-------------------+
| -   The power supply used must be       | **C** |                   |
|     battery powered and should include  |       |                   |
|     a safety cutout.                    |       |                   |
|                                         |       |                   |
|     -   Monitoring of the current must  |       |                   |
|         be carried out throughout       |       |                   |
|         iontophoresis where possible.   |       |                   |
|         Wescor systems from model 3600  |       |                   |
|         onwards have no ammeter but     |       |                   |
|         have an appropriate safety cut  |       |                   |
|         out system.                     |       |                   |
|                                         |       |                   |
|     -   The power supply and electrodes |       |                   |
|         must be regularly checked,      |       |                   |
|         maintained and records kept.    |       |                   |
|                                         |       |                   |
|     -   Electrical safety of all power  |       |                   |
|         supplies must be checked        |       |                   |
|         annually.                       |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Electrodes should be of a suitable  | **C** |                   |
|     size and curvature to fit snugly on |       |                   |
|     the patient\'s limb.                |       |                   |
|                                         |       |                   |
|     -   They are most commonly made of  |       |                   |
|         copper or stainless steel.      |       |                   |
|                                         |       |                   |
|     -   Electrodes should be firmly     |       |                   |
|         secured in position to the      |       |                   |
|         electrolyte support pads or     |       |                   |
|         gels using straps that are      |       |                   |
|         adjustable to fit the patient   |       |                   |
|         (e.g. Velcro or rubber).        |       |                   |
|                                         |       |                   |
|     -   Electrodes must be regularly    |       |                   |
|         cleaned and inspected, and      |       |                   |
|         discarded if they show pitting  |       |                   |
|         or irregularities.              |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Selection of new equipment, and     | **C** |                   |
|     maintenance of existing equipment,  |       |                   |
|     must comply with Clinical Pathology |       |                   |
|     Accreditation (CPA) (or equivalent  |       |                   |
|     standard).                          |       |                   |
+-----------------------------------------+-------+-------------------+
| **Electrolyte Solutions**               | **B** | (Price & Spencer, |
|                                         |       | 1977; Szabo,      |
| -   Aqueous solutions or Wescor gel     |       | Kenny, & Lee,     |
|     discs containing pilocarpine        |       | 1973)             |
|     nitrate at 2-5 g/l are recommended  |       |                   |
|     for use at both electrodes.         |       |                   |
|     Alternative solutions (e.g.         |       |                   |
|     magnesium sulphate) may be used at  |       |                   |
|     the cathode.                        |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Solutions containing sodium and/or  | **C** |                   |
|     chloride should be avoided because  |       |                   |
|     of the risk of contamination of the |       |                   |
|     collection.                         |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Unbuffered acid solutions should    | **B** | (Schwarz,         |
|     not be used because of the          |       | Sutcliffe, &      |
|     increased risk of burns.            |       | Style, 1968)      |
+-----------------------------------------+-------+-------------------+
| -   Electrolytes used for iontophoresis | **C** |                   |
|     must either be obtained as part of  |       |                   |
|     a medical device (e.g. Wescor       |       |                   |
|     Pilogel Discs) or from a recognised |       |                   |
|     manufacturer of unlicensed medical  |       |                   |
|     products. Solutions must not be     |       |                   |
|     produced in-house by hospital       |       |                   |
|     laboratories.                       |       |                   |
+-----------------------------------------+-------+-------------------+
| **Electrolyte Supports**                | **B** | (Schwarz,         |
|                                         |       | Sutcliffe, &      |
| -   Suitably thick pads must be used    |       | Style, 1968)      |
|     for the electrolyte solutions to    |       |                   |
|     minimise the risk of acid burns.    |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Pads of Hospital Lint BPC Plain 500 | **Not |                   |
|     gram folded to provide 4-8          | Grade |                   |
|     thicknesses (greater than 1 cm      | d\*** |                   |
|     thick) are recommended as an        |       |                   |
|     electrolyte reservoir with filter   |       |                   |
|     paper collection systems. The pad   |       |                   |
|     should be at least 1 cm larger than |       |                   |
|     the electrode in all directions to  |       |                   |
|     prevent electrode-skin contact. It  |       |                   |
|     may be incorporated into sewn       |       |                   |
|     pockets designed to contain the     |       |                   |
|     electrode and prevent skin contact. |       |                   |
|     The pads should be saturated by     |       |                   |
|     soaking in the electrolyte solution |       |                   |
|     before application to the           |       |                   |
|     patient\'s skin.                    |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Hybrid systems (e.g. Wescor         | **Not |                   |
|     electrodes with aqueous electrolyte | Grade |                   |
|     solutions, or Wescor gel discs used | d\*** |                   |
|     with non-Wescor electrodes) should  |       |                   |
|     not be used.                        |       |                   |
+-----------------------------------------+-------+-------------------+
| **Iontophoresis - time, current**       | **B** | (Instruction      |
|                                         |       | manual, 1979;     |
| -   When aqueous electrolyte solutions  |       | Price & Spencer,  |
|     are applied on pad supports to a    |       | 1977; Gibson &    |
|     current of 0.5 mA should be         |       | Cooke, 1959;      |
|     applied, and increased gradually to |       | Webster & Barlow, |
|     a maximum of 4 mA. Once 4 mA is     |       | 1981; Webster,    |
|     attained the current should be      |       | 1983; Kirk et     |
|     maintained for a minimum of 3       |       | al., 1983)        |
|     minutes and a maximum of 5 minutes. |       |                   |
|     Longer times should be necessary to |       |                   |
|     increase sweat production, provided |       |                   |
|     good electrical contact is          |       |                   |
|     maintained, by use of well          |       |                   |
|     maintained electrodes and suitably  |       |                   |
|     saturated pads.                     |       |                   |
+-----------------------------------------+-------+-------------------+
| -   When Wescor systems are used, the   | **C** |                   |
|     manufacturer\'s current and time    |       |                   |
|     recommendations should be followed. |       |                   |
|     This will depend on the specific    |       |                   |
|     model used.                         |       |                   |
+-----------------------------------------+-------+-------------------+
| -   For both systems, the patient must  | **C** |                   |
|     be kept under close supervision     |       |                   |
|     throughout the iontophoresis        |       |                   |
|     period.                             |       |                   |
+-----------------------------------------+-------+-------------------+
| **Medium of Collection**                | **C** |                   |
|                                         |       |                   |
| -   During collection, sweat must be    |       |                   |
|     protected from contamination and    |       |                   |
|     evaporation (see example SOP in the |       |                   |
|     original guideline document).       |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat should be collected onto      | **C** |                   |
|     preweighed sodium chloride free     |       |                   |
|     filter paper or Wescor disposable   |       |                   |
|     collectors.                         |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The size of the filter paper should | **C** |                   |
|     be approximately equal to the area  |       |                   |
|     stimulated (i.e. the size of the    |       |                   |
|     electrolyte support pads).          |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Filter paper should be covered with | **C** |                   |
|     a sheet of impervious material at   |       |                   |
|     least 1 cm larger in all dimensions |       |                   |
|     than the filter paper.              |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The impervious material must be     | **C** |                   |
|     completely sealed to the skin       |       |                   |
|     surface using a suitable adhesive   |       |                   |
|     tape.                               |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Filter paper and the inner side of  | **C** |                   |
|     the impervious material must never  |       |                   |
|     come into direct contact with the   |       |                   |
|     operator\'s hands.                  |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Wescor collectors should be used    | **C** |                   |
|     according to the manufacturer\'s    |       |                   |
|     instructions, taking precautions to |       |                   |
|     avoid direct contact of the sweat   |       |                   |
|     collecting surface with the         |       |                   |
|     operator\'s hands.                  |       |                   |
+-----------------------------------------+-------+-------------------+
| **Collection Time**                     | **B** | (Reynolds,        |
|                                         |       | personal          |
| -   Sweat should be collected for not   |       | communication ;   |
|     more than 30 minutes and not less   |       | Price & Spencer,  |
|     than 20 minutes.                    |       | 1977; Shwachman & |
|                                         |       | Mahmoodian, 1966; |
|                                         |       | Webster &         |
|                                         |       | Quirante, 2000;   |
|                                         |       | Webster & Barlow, |
|                                         |       | 1981; Kirk et     |
|                                         |       | al., 1983;        |
|                                         |       | Simmonds et al.,  |
|                                         |       | 1989; Gibson & di |
|                                         |       | Sant\'Agnese,     |
|                                         |       | 1963; Schwarz,    |
|                                         |       | Simpson, & Ahuja, |
|                                         |       | 1977; Hjelm,      |
|                                         |       | Brown, & Briddon, |
|                                         |       | 1986)             |
+-----------------------------------------+-------+-------------------+
| -   The Orion electrode should not be   | **B** | (Price & Spencer, |
|     used.                               |       | 1977; Denning et  |
|                                         |       | al., 1980)        |
+-----------------------------------------+-------+-------------------+
| **Sweat Analysis\                       |       |                   |
| \                                       |       |                   |
| Pre-analytical**                        |       |                   |
+-----------------------------------------+-------+-------------------+
| **Storage before analysis**             | **C** |                   |
|                                         |       |                   |
| -   Throughout sweat collection         |       |                   |
|     (including transport and analysis)  |       |                   |
|     every effort should be made to      |       |                   |
|     minimise evaporation of the sample. |       |                   |
+-----------------------------------------+-------+-------------------+
| -   If storage is necessary before      | **B** | (Legrys, 1993)    |
|     analysis, sweat collections on      |       |                   |
|     paper pads should be kept at 4      |       |                   |
|     degrees Celsius for a maximum of 3  |       |                   |
|     days and in appropriately sized,    |       |                   |
|     air tight containers which do not   |       |                   |
|     allow leakage or evaporation.       |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Liquid sweat from Macroduct         | **B** | (Kirk, personal   |
|     collections can be stored in sealed |       | communication,    |
|     macroduct tubing for up to 72 hours |       | 2001;             |
|     at 4 degrees Celsius. Haematocrit   |       | Fahie-Wilson &    |
|     tubes sealed with plasticine are    |       | Freedman, 1995)   |
|     also suitable, providing an air gap |       |                   |
|     is left between plasticine and      |       |                   |
|     sweat.                              |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat may be collected at remote    | **B** |                   |
|     sites and transported to the        |       |                   |
|     laboratory for analysis provided    |       |                   |
|     there is attention to storage       |       |                   |
|     details.                            |       |                   |
+-----------------------------------------+-------+-------------------+
| **Weighing**                            |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The same balance must be used       | **C** |                   |
|     throughout.                         |       |                   |
+-----------------------------------------+-------+-------------------+
| -   A balance sensitive to 0.0001 g     | **C** |                   |
|     must be used to weigh sweat.        |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat collections onto paper pads   | **C** |                   |
|     should be weighed and analysed as   |       |                   |
|     soon as practicable.                |       |                   |
+-----------------------------------------+-------+-------------------+
| **Definition of adequate sample**       | **B** | (Price & Spencer, |
|                                         |       | 1977; Webster &   |
| -   The sweat secretion rate measured   |       | Quirante, 2000;   |
|     as an average rate over the         |       | Kirk et al.,      |
|     collection period should not be     |       | 1983; Simmonds et |
|     less than 1 g/m^2^/min. Collections |       | al., 1989; Hjelm, |
|     below this rate should not be       |       | Brown, & Briddon, |
|     analysed. Insufficient sweat        |       | 1986; Gibson & de |
|     collections should not be pooled.   |       | Sant\'Agnese,     |
|     The full sweat test should be       |       | 1963)             |
|     repeated.                           |       |                   |
+-----------------------------------------+-------+-------------------+
| **Analysis**                            |       |                   |
+-----------------------------------------+-------+-------------------+
| **Elution of sweat from filter paper**  | **C** |                   |
|                                         |       |                   |
| -   When sweat is collected onto filter |       |                   |
|     paper (refer to section 3.2.1 of    |       |                   |
|     the original guideline document) it |       |                   |
|     should be eluted for a minimum of   |       |                   |
|     40 minutes.                         |       |                   |
+-----------------------------------------+-------+-------------------+
| **Analytes**                            | **B** | (Green, Dodds, &  |
|                                         |       | Pennock, 1985;    |
| -   Sweat chloride concentration should |       | Hall,             |
|     be measured.                        |       | Stableforth, &    |
|                                         |       | Green, 1990;      |
|                                         |       | Gleeson & Henry,  |
|                                         |       | 1991, Kirk et     |
|                                         |       | al., 1992)        |
+-----------------------------------------+-------+-------------------+
| -   Sweat sodium must not be the only   | **B** | (Green, Dodds, &  |
|     or primary analyte measured.        |       | Pennock, 1985;    |
|                                         |       | Hall,             |
|                                         |       | Stableforth, &    |
|                                         |       | Green, 1990;      |
|                                         |       | Gleeson & Henry,  |
|                                         |       | 1991, Kirk et     |
|                                         |       | al., 1992)        |
+-----------------------------------------+-------+-------------------+
| -   Sweat potassium measurement is not  | **B** | (Shwachman,       |
|     recommended.                        |       | Mahmoodian, &     |
|                                         |       | Neff, 1981)       |
+-----------------------------------------+-------+-------------------+
| -   Sweat conductivity measurement for  | **B** | (Heeley, Woolf, & |
|     the investigation of cystic         |       | Heeley, 2000;     |
|     fibrosis (CF) requires further      |       | Mastella et al.,  |
|     study. If conductivity is measured, |       | 2000; Legrys,     |
|     sweat chloride should also be       |       | 2001; Heeley,     |
|     measured until the relative merits  |       | Woolf, & Heeley,  |
|     of conductivity have been           |       | 2001; Webster,    |
|     established.                        |       | 2001)             |
+-----------------------------------------+-------+-------------------+
| -   Sweat osmolality measurement is not | **B** | (Kirk, personal   |
|     recommended.                        |       | communication,    |
|                                         |       | 2001; Heeley,     |
|                                         |       | Woolf, & Heeley,  |
|                                         |       | 2000)             |
+-----------------------------------------+-------+-------------------+
| **Methodology**                         | **B** | (Fahie-Wilson and |
|                                         |       | Freedman, 1995;   |
| -   Colorimetry, coulometry and ion     |       | Finlay MacKenzie, |
|     selective electrodes (ISEs) are     |       | 2001; Heeley,     |
|     satisfactory methods for analysis   |       | Woolf, & Heeley,  |
|     of sweat chloride.                  |       | 2000)             |
+-----------------------------------------+-------+-------------------+
| -   Flame photometry or ion selective   | **B** | (Finlay           |
|     electrodes are satisfactory methods |       | MacKenzie, 2001;  |
|     for analysis of sweat sodium.       |       | Barbour, 1991;    |
|                                         |       | Northall & York,  |
|                                         |       | 1995)             |
+-----------------------------------------+-------+-------------------+
| -   Conductivity measurement using the  | **B** | (Finlay           |
|     Wescor equipment is a satisfactory  |       | MacKenzie, 2001;  |
|     method of analysis.                 |       | Heeley, Woolf, &  |
|                                         |       | Heeley, 2000)     |
+-----------------------------------------+-------+-------------------+
| **Report format**                       | **C** |                   |
|                                         |       |                   |
| The report format should include:       |       |                   |
|                                         |       |                   |
| i.  Full patient identification         |       |                   |
|                                         |       |                   |
| ii. Date and time of test and date and  |       |                   |
|     time of report                      |       |                   |
|                                         |       |                   |
| iii. Sweat weight/volume collected and  |       |                   |
|      minimum weight/volume acceptable   |       |                   |
|      for local sweat test parameters    |       |                   |
|                                         |       |                   |
| iv. Analytical results (mmol/L)         |       |                   |
|                                         |       |                   |
| > **It should be explicit on the report |       |                   |
| > form which analyte(s) have been       |       |                   |
| > measured** (i.e., chloride, sodium,   |       |                   |
| > conductivity \[sodium chloride        |       |                   |
| > equivalent\])**.**                    |       |                   |
|                                         |       |                   |
| v.  Reference ranges (see section 6 of  |       |                   |
|     the original guideline document)    |       |                   |
|                                         |       |                   |
| vi. Interpretation of the results (see  |       |                   |
|     section 6 of the original guideline |       |                   |
|     document)                           |       |                   |
|                                         |       |                   |
| vii. Recommendations for repeat testing |       |                   |
|      if appropriate (see section 6.9 of |       |                   |
|      the original guideline document)   |       |                   |
+-----------------------------------------+-------+-------------------+
| **Quality**                             |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat which has been subject to     | **C** |                   |
|     evaporation and/or contamination    |       |                   |
|     must not be measured.               |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The analytical range of the methods | **C** |                   |
|     used must cover the concentration   |       |                   |
|     ranges found in normals and         |       |                   |
|     subjects with CF.                   |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The analytical methods must be      | **C** |                   |
|     fully documented as SOP to comply   |       |                   |
|     with Clinical Pathology             |       |                   |
|     Accreditation (or equivalent        |       |                   |
|     standard). The SOP must include the |       |                   |
|     analytical method(s), quality       |       |                   |
|     procedures, reporting,              |       |                   |
|     interpretation and safety aspects.  |       |                   |
|                                         |       |                   |
| > An example SOP is provided (see       |       |                   |
| > Appendix Documents 2a and 2b of the   |       |                   |
| > original guideline document).         |       |                   |
+-----------------------------------------+-------+-------------------+
| -   There must be an internal quality   | **C** |                   |
|     procedure (which differs from the   |       |                   |
|     calibration/standardisation         |       |                   |
|     procedure) at two concentrations    |       |                   |
|     (normal and intermediate or         |       |                   |
|     abnormal) for each analysis.        |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The analytical methods should each  | **B** | (Heeley, Woolf, & |
|     have a between batch coefficient of |       | Heeley, 2000;     |
|     variation (CV) of 5% (or less) at a |       | Hall,             |
|     concentration of 40-50 mmol/L.      |       | Stableforth, &    |
|                                         |       | Green, 1990;      |
|                                         |       | Hammond, Turcios, |
|                                         |       | & Gibson, 1994;   |
|                                         |       | Kirk et al, 1992; |
|                                         |       | Ayers, 2000;      |
|                                         |       | Taylor & James,   |
|                                         |       | 1996)             |
+-----------------------------------------+-------+-------------------+
| -   The laboratory must participate in  | **C** |                   |
|     a suitable external quality         |       |                   |
|     assessment scheme.                  |       |                   |
+-----------------------------------------+-------+-------------------+
| -   If chloride and sodium              | **B** |                   |
|     concentrations are widely           |       |                   |
|     discrepant, the test should be      |       |                   |
|     repeated.                           |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Results which are not physiological | **B** | (Schulz, 1969)    |
|     should be questioned (i.e. chloride |       |                   |
|     or sodium \> 150 mmol/L).           |       |                   |
+-----------------------------------------+-------+-------------------+
| -   For conductivity a provisional      | **C** |                   |
|     upper physiological limit of 170    |       |                   |
|     mmol/L may be used pending further  |       |                   |
|     evidence.                           |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Failed sweat collections (i.e.      | **C** |                   |
|     insufficient weight or volume)      |       |                   |
|     should not exceed 10% of the tested |       |                   |
|     population (excluding repeats and   |       |                   |
|     tests carried out in sick/very      |       |                   |
|     young patients). There should be a  |       |                   |
|     target of 5%.                       |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Performance of sweat testing should | **C** |                   |
|     be reviewed on a regular basis.     |       |                   |
|     This should include:                |       |                   |
|                                         |       |                   |
|     -   Insufficient collections        |       |                   |
|                                         |       |                   |
|         -   as % of total tests         |       |                   |
|                                         |       |                   |
|         -   per operator                |       |                   |
|                                         |       |                   |
|     -   Analytical failure rate (i.e. % |       |                   |
|         outside accepted quality        |       |                   |
|         control (QC) range)             |       |                   |
|                                         |       |                   |
|     -   External quality assessment     |       |                   |
|         performance                     |       |                   |
+-----------------------------------------+-------+-------------------+
| The laboratory should work with         | **C** |                   |
| clinicians to audit sweat test results, |       |                   |
| in particular repeat collections,       |       |                   |
| diagnoses and outcome of positive and   |       |                   |
| intermediate results on a regular basis |       |                   |
| (see section 8 of the original          |       |                   |
| guideline document).                    |       |                   |
+-----------------------------------------+-------+-------------------+
| **Interpretation of sweat               |       |                   |
| electrolytes**                          |       |                   |
+-----------------------------------------+-------+-------------------+
| The following definitions are           | **B** | (Green, Dodds, &  |
| recommended for interpretation:         |       | Pennock, 1985;    |
|                                         |       | Hall,             |
| -   A sweat chloride concentration of   |       | Stableforth, &    |
|     \>60 mmol/L supports the diagnosis  |       | Green, 1990;      |
|     of CF                               |       | Rosenstein, 1999; |
|                                         |       | Rosenstein &      |
|                                         |       | Cutting, 1998;    |
|                                         |       | Farrell & Koscik, |
|                                         |       | 1996;             |
|                                         |       | \"Correlation     |
|                                         |       | between genotype  |
|                                         |       | and phenotype,\"  |
|                                         |       | 1993; Davis et    |
|                                         |       | al., 1983; di     |
|                                         |       | Sant\'Agnese et   |
|                                         |       | al., 1953)        |
+-----------------------------------------+-------+-------------------+
| -   Intermediate chloride concentration | **B** | (Green, Dodds, &  |
|     of 40-60 mmol/L is suggestive but   |       | Pennock, 1985;    |
|     not diagnostic of CF.               |       | Hall,             |
|                                         |       | Stableforth, &    |
|                                         |       | Green, 1990;      |
|                                         |       | Rosenstein, 1999; |
|                                         |       | Rosenstein &      |
|                                         |       | Cutting, 1998;    |
|                                         |       | Farrell & Koscik, |
|                                         |       | 1996; Correlation |
|                                         |       | between genotype  |
|                                         |       | and phenotype,\"  |
|                                         |       | 1993; Davis et    |
|                                         |       | al., 1983; di     |
|                                         |       | Sant\'Agnese et   |
|                                         |       | al., 1953)        |
+-----------------------------------------+-------+-------------------+
| -   A sweat chloride of less than 40    | **B** | (Green, Dodds, &  |
|     mmol/L is normal and there is a low |       | Pennock, 1985;    |
|     probability of CF.                  |       | Hall,             |
|                                         |       | Stableforth, &    |
|                                         |       | Green, 1990;      |
|                                         |       | Rosenstein, 1999; |
|                                         |       | Rosenstein &      |
|                                         |       | Cutting, 1998;    |
|                                         |       | Farrell & Koscik, |
|                                         |       | 1996;             |
|                                         |       | \"Correlation     |
|                                         |       | between genotype  |
|                                         |       | and phenotype,\"  |
|                                         |       | 1993; Davis et    |
|                                         |       | al., 1983; di     |
|                                         |       | Sant\'Agnese et   |
|                                         |       | al., 1953)        |
+-----------------------------------------+-------+-------------------+
| -   Sodium should not be interpreted    | **B** | (Green, Dodds, &  |
|     without a chloride result.          |       | Pennock, 1985)    |
+-----------------------------------------+-------+-------------------+
| -   Pending further data on             | **B** | (Hammonds,        |
|     conductivity measurements a value   |       | Turcios, &        |
|     below 60 mmol/L (NaCl equivalents)  |       | Gibson, 1994;     |
|     is unlikely to be associated with   |       | Heeley, Woolf, &  |
|     CF. Values above 90 mmol/L support  |       | Heeley, 2000;     |
|     a diagnosis of CF.                  |       | Mastella et al.,  |
|                                         |       | 2000).            |
+-----------------------------------------+-------+-------------------+
| -   CF should not be diagnosed based on | **B** | (Hammonds,        |
|     conductivity measurements alone.    |       | Turcios, &        |
|                                         |       | Gibson, 1994;     |
|                                         |       | Heeley, Woolf, &  |
|                                         |       | Heeley, 2000;     |
|                                         |       | Mastella et al.,  |
|                                         |       | 2000).            |
+-----------------------------------------+-------+-------------------+
| **Repeat Testing**                      | **C** |                   |
|                                         |       |                   |
| -   A repeat sweat test is recommended  |       |                   |
|     when the sweat test result is not   |       |                   |
|     in keeping with the clinical        |       |                   |
|     phenotype and/or genotype.          |       |                   |
+-----------------------------------------+-------+-------------------+
| **Further Investigations**              | **B** | (Augarten et al., |
|                                         |       | 1995; Stern et    |
| -   Mutation analysis can be a useful   |       | al., 1978;        |
|     diagnostic test, particularly in    |       | Highsmith et al., |
|     patients with a mild or atypical    |       | 1994; Augarten et |
|     phenotype where sweat chloride      |       | al., 1993; Strong |
|     concentration may be intermediate.  |       | et al., 1991;     |
|                                         |       | Gilfillan et al., |
|                                         |       | 1998)             |
+-----------------------------------------+-------+-------------------+
| -   Nasal potential difference may be   | **B** | (Rosenstein,      |
|     helpful as a confirmatory           |       | 1999; Alton et    |
|     investigation for the diagnosis.    |       | al., 1987;        |
|                                         |       | Delmarco et al.,  |
|                                         |       | 1997)             |
+-----------------------------------------+-------+-------------------+
| -   There is no routine place for the   | **B** | (Hodson et al.,   |
|     use of the mineralo-corticoid       |       | 1983)             |
|     suppression adaptation of the sweat |       |                   |
|     test.                               |       |                   |
+-----------------------------------------+-------+-------------------+
| **Responsibility for Testing and        |       |                   |
| Training**                              |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat collection must be performed  | **C** |                   |
|     by fully trained and experienced    |       |                   |
|     personnel:                          |       |                   |
|                                         |       |                   |
|     -   Training schedules should be    |       |                   |
|         fully documented.               |       |                   |
|                                         |       |                   |
|     -   The procedure should be         |       |                   |
|         documented as an SOP.           |       |                   |
|                                         |       |                   |
|     -   Appropriate revalidation        |       |                   |
|         procedures should be in place.  |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat collection can be undertaken  | **C** |                   |
|     by a variety of health              |       |                   |
|     professionals.                      |       |                   |
+-----------------------------------------+-------+-------------------+
| -   Sweat analysis should be performed  | **C** |                   |
|     by qualified and experienced        |       |                   |
|     biomedical scientists or clinical   |       |                   |
|     scientists who are fully trained    |       |                   |
|     with regular validation:            |       |                   |
|                                         |       |                   |
|     -   Training and validation         |       |                   |
|         schedules should be fully       |       |                   |
|         documented.                     |       |                   |
+-----------------------------------------+-------+-------------------+
| -   A consultant (or equivalent)        | **C** |                   |
|     clinical chemist should have        |       |                   |
|     responsibility for training,        |       |                   |
|     assessment of competence and        |       |                   |
|     revalidation for all staff          |       |                   |
|     undertaking sweat tests.            |       |                   |
+-----------------------------------------+-------+-------------------+
| -   A minimum number of 50 sweat tests  | **C** |                   |
|     per annum should be performed in    |       |                   |
|     any one centre.                     |       |                   |
+-----------------------------------------+-------+-------------------+
| -   A minimum of 10 collection          | **C** |                   |
|     procedures should be performed per  |       |                   |
|     person per annum.                   |       |                   |
+-----------------------------------------+-------+-------------------+
| -   The **responsibilities** for sweat  | **C** |                   |
|     testing, both collection and        |       |                   |
|     analytical, should rest with a      |       |                   |
|     consultant (or equivalent) clinical |       |                   |
|     chemist and should be clearly       |       |                   |
|     understood by all operators and     |       |                   |
|     users; a mechanism for reporting    |       |                   |
|     any concerns about performance      |       |                   |
|     should be in place and clearly      |       |                   |
|     understood.                         |       |                   |
+-----------------------------------------+-------+-------------------+

> \* Grading of this recommendation changed following appraisal by the
> Royal College of Paediatrics and Child Health.
>
> **Definitions**:
>
> **Levels of Evidence**
>
> The levels of evidence are based on the U.S. Agency for Health Care
> Policy (AHCPR) 1992
>
> **I a**: Evidence obtained from meta-analysis of randomised controlled
> trials
>
> **I b**: Evidence obtained from at least one randomised controlled
> trial
>
> **II a**: Evidence obtained from at least one well designed controlled
> study without randomisation
>
> **II b**: Evidence from at least one other type of quasi-experimental
> descriptive study
>
> **III**: Evidence obtained from well designed, nonexperimental
> descriptive studies such as comparative studies, correlation studies
> and case studies
>
> **IV**: Evidence obtained from expert committee reports or opinions
> and/or clinical experience of respected authorities
>
> [Note]{.underline}: The guideline development group felt that the
> Scottish Intercollegiate Guidelines Network (SIGN) criteria,
> particularly IIb and III, are sometimes difficult to interpret in the
> context of performance of a laboratory diagnostic test. The working
> group has interpreted these levels as follows:
>
> **IIb**

-   A planned scientific study with hypothesis

-   A study not controlled

-   An experimental study, with a low risk of bias

> **III**

-   Nonexperimental/observational study

-   Investigation of a standard procedure

> **Grading of Recommendations**
>
> The criteria for the grading of recommendations in this document are
> based upon those used by the U.S. Agency for Health Care Policy and
> Research (AHCPR), and published by the SIGN\*\*
>
> **A (levels I a and I b)**: Requires at least one randomised
> controlled trial as part of the body of literature of overall good
> quality and consistency addressing the specific recommendation
>
> **B (levels II a, II b, III)**: Requires availability of well
> conducted clinical studies but no randomised clinical trials on the
> topic of the recommendation
>
> **C (level IV)**: Requires evidence from expert committee reports or
> opinions and/or clinical experience of respected authorities.
> Indicates absence of directly applicable studies of good quality
>
> \*\*The working group note that the SIGN grading system had been
> revised since work on these guidelines commenced. It was felt that the
> revised version offered no advantage in this instance and, therefore,
> after consultation with the Royal College of Paediatrics & Child
> Health, the original SIGN version has been used.

#### CLINICAL ALGORITHM(S)

> None provided

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### REFERENCES SUPPORTING THE RECOMMENDATIONS

> [References open in a new
> window](http://www.guideline.gov/summary/select_ref.aspx?doc_id=5059)

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

> The type of supporting evidence is identified and graded for each
> recommendation (see \"Major Recommendations\").

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

> The sweat test, a quantitative measurement of electrolytes in sweat,
> remains vital in supporting the clinical diagnosis of cystic fibrosis
> (CF).

#### POTENTIAL HARMS

-   There are published reports and personal communications which report
    clinical experience of the poor performance of sweat testing leading
    to an incorrect diagnosis. False negative results are of particular
    concern due to the potential for diagnostic delay. There is concern
    about the competency of the operator performing the collection, the
    need for quality control and external assessment to assess method
    performance, the competency of the analyst and interpretation. The
    causes of false positive and false negative results can arise from
    one or more of the following reasons: patients\' physiology,
    inadequate sweat collection, poor/unreliable methodology, poor
    operator technique, misinterpretation.

-   A theoretical risk of atrial fibrillation has never been documented.

-   Burns or blisters are sporadically reported resulting from
    electrode-skin contact or inadequate reservoir of electrolyte
    solution between skin and electrode.

-   Pilocarpine is toxic to eyes and skin.

-   Sweat is considered to be a biohazard.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

> An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

> Patient Resources\
> Staff Training/Competency Material
>
> For information about
> [availability](#identifying-information-and-availability), see the
> \"Availability of Companion Documents\" and \"Patient Resources\"
> fields below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

> Staying Healthy

#### IOM DOMAIN

> Effectiveness\
> Safety

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

> Guidelines for the performance of the sweat test for the investigation
> of cystic fibrosis in the UK. London: Royal College of Paediatrics and
> Child Health; 2003 Nov 1. 97 p. \[123 references\]

#### ADAPTATION

> Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

> 2003 Nov

#### GUIDELINE DEVELOPER(S)

> Association of Clinical Biochemists - Professional Association

#### GUIDELINE DEVELOPER COMMENT

> The Multi-Disciplinary Working Group included representatives from the
> following organizations:

-   UK National External Quality Assessment Schemes

-   British Thoracic Society and Cystic Fibrosis Trust

-   Royal College of Pathologists

-   Royal College of Paediatrics & Child Health

-   British Paediatric Respiratory Society

#### SOURCE(S) OF FUNDING

> Association of Clinical Biochemists
>
> Royal College of Pathologists
>
> Royal College of Paediatrics and Child Health

#### GUIDELINE COMMITTEE

> Guidelines Development Group

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

> *Group Members*: Dr. Anne Green (Chairman) Consultant Biochemist,
> Birmingham Children\'s Hospital NHSTrust; Professor Stuart Elborn,
> Consultant Physician, Belfast City Hospital, Belfast; Mr. Mike N.
> Fahie-Wilson, Principal Biochemist, Southend Hospital,
> Westcliff-on-Sea; Dr. Jean M. Kirk, Consultant Biochemist, Royal
> Hospital for Sick Children, Edinburgh, Lothian University Hospitals
> NHSTrust; Dr. Colin E. Wallis, Consultant Paediatrician, Great Ormond
> Street Hospital, London; Dr. Peter Weller, Consultant Paediatrician in
> Respiratory Medicine, Birmingham Children\'s Hospital NHS Trust

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

> Not stated

#### ENDORSER(S)

> Royal College of Paediatrics and Child Health - Academic Institution

#### GUIDELINE STATUS

> This is the current release of the guideline.

#### GUIDELINE AVAILABILITY

> Electronic copies: Available in Portable Document Format (PDF) from
> the [Association of Clinical Biochemists Web
> site](http://www.acb.org.uk/Guidelines/STNov03.pdf).
>
> Print copies: Available from Dr. Anne Green, Consultant Paediatric
> Biochemist, Birmingham Children\'s Hospital, Steelhouse Lane,
> Birmingham, B4 6NH. Phone: (0121) 333 9922. Email:
> <anne.green@bch.nhs.uk>

#### AVAILABILITY OF COMPANION DOCUMENTS

> The following is available:

-   Sweat testing procedure. Staff training material. In: Guidelines for
    the performance of the sweat test for the investigation of cystic
    fibrosis in the UK. London: Royal College of Paediatrics and Child
    Health; 2003. p. 81-7.

> Electronic copies: Available in Portable Document Format (PDF) from
> the [Association of Clinical Biochemists Web
> site](http://www.acb.org.uk/Guidelines/STNov03.pdf).
>
> Print copies: Available from Dr. Anne Green, Consultant Paediatric
> Biochemist, Birmingham Children\'s Hospital, Steelhouse Lane,
> Birmingham, B4 6NH. Phone: (0121) 333 9922. Email:
> <anne.green@bch.nhs.uk>

#### PATIENT RESOURCES

> The following is available:

-   Example sweat test information sheet for patients/parents. In:
    Guidelines for the performance of the sweat test for the
    investigation of cystic fibrosis in the UK. London: Royal College of
    Paediatrics and Child Health; 2003. p. 79-80.

> Electronic copies: Available in Portable Document Format (PDF) from
> the [Association of Clinical Biochemists Web
> site](http://www.acb.org.uk/Guidelines/STNov03.pdf).
>
> Print copies: Available from Dr. Anne Green, Consultant Paediatric
> Biochemist, Birmingham Children\'s Hospital, Steelhouse Lane,
> Birmingham, B4 6NH. Phone: (0121) 333 9922. Email:
> <anne.green@bch.nhs.uk>
>
> Please note: This patient information is intended to provide health
> professionals with information to share with their patients to help
> them better understand their health and their diagnosed disorders. By
> providing access to this patient information, it is not the intention
> of NGC to provide specific medical advice for particular patients.
> Rather we urge patients and their representatives to review this
> material and then to consult with a licensed health professional for
> evaluation of treatment options suitable for them as well as for
> diagnosis and answers to their personal medical questions. This
> patient information has been derived and prepared from a guideline for
> health care professionals included on NGC by the authors or publishers
> of that original guideline. The patient information is not reviewed by
> NGC to establish whether or not it accurately reflects the original
> guideline\'s content.

#### NGC STATUS

> This summary was completed by ECRI on January 21, 2005. The
> information was verified by the guideline developer on February 11,
> 2005.

#### COPYRIGHT STATEMENT

> This NGC summary is based on the original guideline, which is subject
> to the guideline developer\'s copyright restrictions.

### DISCLAIMER

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> © 1998-2008 National Guideline Clearinghouse
>
> Date Modified: 11/3/2008
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