Newsgroup: it.salute
Titolo: mineralogramma

Alcune domande che spero qualche esperto sappia esaudire.
Il mineralogramma è utile?
E' diffuso?
Dove lo potrei fare? All'ospedale, in farmacia, in palestra?
I medici lo conoscono? Lo usano?
Ma è vero che si fa anche sugli animali e si applica anche
all'agricoltura?
Grazie a chi avrà la pazienza di delucidarmi.
Luis
-- 
Posted via Mailgate.ORG Server - 
http://www.Mailgate.ORG

 Il mineralogramma è utile?
mah ?
non sono proprio un esperto ma ci sono dei forti sospetti che spesso sia
...... "na' strunzata "
http://jama.ama-assn.org/issues/v285n1/ffull/jed00095.html
The Uncertainty of Hair Analysis for Trace Metals
 Steven J. Steindel, PhD; Peter J. Howanitz, MD
In 1985, an article by Barrett1 published in THE JOURNAL addressed several
issues related to the use of trace metal hair analysis for assessing
nutritional status. Now, in this issue of THE JOURNAL, Seidel and colleagues
show that many of same concerns raised 15 years ago by Barrett's study
remain unresolved. Both studies used a self-prepared split sample that was
sent to several laboratories specializing in trace metal analysis of human
hair. Both noted the divergence of results obtained and the health-related
claims made. Seidel et al also commented on the current regulatory
environment that hair analysis laboratories now face.
Accuracy of laboratory tests is best ensured through the use of standards of
known value to calibrate tests. Internationally recognized groups, such as
the National Institute of Science and Technology, provide standard materials
of known value, and other organizations, such as the US Environmental
Protection Agency, provide specifications for these standards.
Unfortunately, there are few primary standards for clinical laboratory
tests. This is, in part, because of the complex interactions between the
proteins (structural, functional, or immunological) and molecules of
interest.3 Hence, clinical laboratory tests most commonly are standardized
through the use of split sample results analyzed using compatible methods
assessed through the proficiency testing (PT) process.
In 1948, Sunderman4 was the first to present the results of PT for common
clinical analytes, and by the mid-1960s, laboratory use of PT samples to
ensure standardization was commonplace. The Clinical Laboratory Improvement
Act (CLIA) of 1967 required all US laboratories engaged in interstate
commerce to use PT, and in 1988, the CLIA was amended to require PT for all
laboratories except those doing simple (waived) testing.5 The widespread use
of PT has helped to drive laboratories toward these interchangeable results.
As noted by Seidel et al, PT does not exist for trace metal hair analysis.
Under CLIA regulations, if PT is not available, the laboratory must use
other methods to ensure the accuracy of the test, perhaps by splitting
samples between peer laboratories at least twice a year.5 As noted, all of
the laboratories used for the study by Seidel et al claimed CLIA
certification, although one perhaps falsely, and no note was made of the
methods used to verify the accuracy of test results among laboratories.
Laboratorians express the dispersion of results found in PT through the
coefficient of variation (CV = SD/mean) expressed as a percentage. For most
common analytes, interlaboratory CVs for PT are less than 10% and usually
less than 5%.6 For more exotic analytes, such as follicle-stimulating
hormone, human growth hormone, or luteinizing hormone, level-dependent
interlaboratory CVs between 15% and 50% are common.7 Based on the data
presented by Seidel et al, the interlaboratory CVs were calculated as 9.8%
for sulfur for the lowest and 238.1% for phosphorous for the highest. The
mean CV was 103.5%, indicating that a factor of 4 encompasses 95% of the
results, which easily explains why the authors have little confidence in the
laboratory results.
Biological specimens, such as those containing the trace metals measured in
this study, frequently are subject to contamination, especially when the
analyte is ubiquitous. The exposure of hair to the environment8, 9 and the
chemical treatment of hair for cosmetic purposes10, 11 ensure that
contamination is a frequent occurrence. No consensus treatment of samples
has been developed for removing such contamination12-14; some reports
indicate that the total removal of contaminants may be impossible.15 Seidel
et al indicate in their study that all laboratories except one performed a
variety of methods in attempting to remove external contamination, although
complete details were not provided. It is likely that some of the deviations
of results may be related to the effectiveness of these methods attempted by
laboratories to remove the external contaminants.
Proteins are known for their ability to bind both small molecules and trace
metals. For an analysis to be reproducible, all of the material must be in a
form that can be measured, a factor laboratorians refer to as "recovery."
For hair analysis by the 2 methods used in the study by Seidel et al, the
trace metals must be free of all protein and occur in a form that can be
readily ionized as required for measurement. No discussion is given as to
the various digestion methods used to prepare the sample, but again, no
consensus exists among laboratories, and diverse methods may yield disparate
results.16, 17
Moreover, the variability of the submitted sample may influence results. The
authors discuss the preparation of their sample but give no indication of
homogeneity. Homogeneity of PT material is difficult to obtain18 and even
more so in solid material such as hair. For solids, a well-mixed powder is
generally considered the best form for distribution.19 The authors most
likely chose not to distribute the samples as powder, which differs greatly
from the usually submitted specimens. Also, it is unclear if the
distribution of heavy metals in the hair shaft is uniform from shaft to
shaft or within the shaft. It is easy to envision the scenario in which
pockets of trace metals collect in areas that differ from hair to hair and
within the hair shaft, and thus, results in a heterogeneous sample, again
perhaps explaining the differences observed among the laboratories.20, 21
Hence, reasonable explanations exist for the observed extreme disparity in
interlaboratory results that are independent of the quality of the
laboratory methods. Does this help practicing clinicians in choosing a
laboratory if they wish to recommend hair analysis? The answer is no. Until
laboratorians reach an agreement on how to standardize both methods and
materials for hair analysis, the large differences among laboratory results
will persist. The call by Seidel et al for increased regulation by the
Health Care Financing Administration (HCFA) will not alone resolve the
problem. Regulation is most effective when the profession identifies one or
more correct solutions that can be recommended. Clearly this does not exist
and has not existed for several decades for hair analysis. In considering a
laboratory for hair analysis, clinicians must understand that a standard
method does not exist. A sample for hair analysis is best sent first to a
laboratory that can validate its certification or accreditation for
performing the test and that reports test characteristics, such as the
hair-washing method, digestion techniques, recovery rates for the elements,
internal quality control performance over time, and the minimum detection
limits for each element.
In addition, the study by Seidel et al focuses on the use of hair for trace
metal determination and the utility for nutritional assessments. Hair
analysis may have some value in determining toxic exposure of heavy metals,
especially over time, but analyses of other specimen types, such as urine,
are more reliable and should be considered first.22 Hair also is becoming an
accepted specimen for identifying some drugs of abuse, although some of the
same issues of standardization and interpretation of results remain, but to
a lesser extent.23
Ultimately, the more important question is does hair analysis have a place
in routine medical practice for assessment of nutritional status? Busy
practitioners may have to address issues related to hair analysis in the
short time that they have with a patient. In addition to traditional issues
about appropriate test use, patients may have evaluated hundreds of Internet
sites for hair analysis as well as an interpretation of their own results
obtained from laboratories providing the service.
Considering that current laboratory methods make it difficult, if not
impossible, to separate endogenous from exogenous material, it is currently
unclear which of these each laboratory actually measures. Until
laboratorians are sure they are measuring endogenous material present in the
sample, it is impossible to relate measurements of individual elements,
ratios of elements, or repeat testing over time to biological conditions.
All results must be interpreted in relation to the laboratories' reference
range for the analyte. At this time, however, it is impossible to relate
results to a "normal person" since this person is difficult to describe with
respect to hair analysis methods, as indicated by the diversity in reference
ranges and laboratory interpretations of "normalcy," as noted by Seidel et
al. Results depend on where patients live (environmental factors), the
biological characteristics of their hair (such as color, thickness, age),
and the cosmetic treatment of the hair (such as external coloring, type of
hair spray, hair gel).
Without an appropriate reference range for a normal person's hair analysis,
it is difficult to determine the clinical significance or nutritional
importance of subtle changes in trace metal values in hair. Similar
positions have been taken by the American Institute of Nutrition/American
Society for Clinical Nutrition24 and the American Medical Association.25
Patients should be advised of the economic consequences of purchasing
vitamin or other nutritional supplements from either the laboratory or the
practitioner ordering the hair analysis test and the uncertainty of any
possible medical consequences based on hair analysis laboratory values.
Physicians and other health care professionals who are considering ordering
hair analysis to assess nutritional status or who are basing nutritional
counseling or therapy on hair analysis results, should reconsider this
approach unless and until the reliability of hair analysis value is
established and evidence becomes available that clinical recommendations
based on hair analysis improve patient outcomes.
REFERENCES
1.
Barrett S.
Commercial hair analysis: science or scam?
JAMA.
1985;254:1041-1045.
MEDLINE
2.
Seidel S, Kreutzer R, Smith D, McNeel S, Gilliss D.
Assessment of commercial laboratories performing hair mineral analysis.
JAMA.
2001;285:67-72.
3.
Miller WG.
How useful are reference materials?
Clin Chem.
1996;42:1733-1734.
MEDLINE
4.
Sunderman FW Sr.
The history of proficiency testing/quality control.
Clin Chem.
1992;38:1205-1209.
MEDLINE
5.
Clinical Laboratory Improvement Amendments of 1988 final rule.
57 Federal Register,
7002-7186 (1992).
6.
Survey 2000 Participant Summary Report: C-A Chemistry.
Northfield, Ill: College of American Pathologists; 2000.
7.
Survey 2000 Participant Summary Report: Y-A Ligands (Special).
Northfield, Ill: College of American Pathologists; 2000.
8.
DeAntonio SM, Katz SA, Scheiner DM, Wood JD.
Anatomically-related variations in trace-metal concentrations in hair.
Clin Chem.
1982;28:2411-2413.
MEDLINE
9.
Wilhelm M, Ohnesorge FK, Lombeck I, Hafner D.
Uptake of aluminum, cadmium, copper, lead, and zinc by human scalp hair and
elution of the adsorbed metals.
J Anal Toxicol.
1989;13:17-21.
MEDLINE
10.
DiPietro ES, Phillips DL, Paschal DC, Neese JW.
Determination of trace elements in human hair: reference intervals for 28
elements in nonoccupationally exposed adults in the US and effects of hair
treatments.
Biol Trace Elem Res.
1989;22:83-100.
MEDLINE
11.
Jurado C, Kintz P, Menendez M, Repetto M.
Influence of the cosmetic treatment of hair on drug testing.
Int J Legal Med.
1997;110:159-163.
MEDLINE
12.
Attar KM, Abdel-Aal MA, Debayle P.
Distribution of trace elements in the lipid and nonlipid matter of hair.
Clin Chem.
1990;36:477-480.
MEDLINE
13.
Assarian GS, Oberleas D.
Effect of washing procedures on trace-element content of hair.
Clin Chem.
1977;23:1771-1772.
MEDLINE
14.
Raghupathy L, Harada M, Ohno H, Naganuma A, Imura N, Doi R.
Methods of removing external metal contamination from hair samples for
environmental monitoring.
Sci Total Environ.
1988;77:141-151.
MEDLINE
15.
Buckley RA, Dreosti IE.
Radioisotopic studies concerning the efficacy of standard washing procedures
for the cleansing of hair before zinc analysis.
Am J Clin Nutr.
1984;40:840-846.
MEDLINE
16.
Puchyr RF, Bass DA, Gajewski R, et al.
Preparation of hair for measurement of elements by inductively coupled
plasma-mass spectrometry (ICP-MS).
Biol Trace Elem Res.
1998;62:167-182.
MEDLINE
17.
Bermejo-Barrera P, Muniz-Naveiro O, Moreda-Pineiro A, Bermejo-Barrera A.
Experimental designs in the optimization of ultrasonic bath-acid-leaching
procedures for the determination of trace elements in human hair samples by
atomic absorption spectrometry.
Forensic Sci Int.
2000;107:105-120.
MEDLINE
18.
Posner A.
Problems in formulating method-insensitive proficiency testing materials.
Arch Pathol Lab Med.
1993;117:422-424.
MEDLINE
19.
Okamoto K, Morita M, Quan H, Uehiro T, Fuwa K.
Preparation and certification of human hair powder reference material.
Clin Chem.
1985;31:1592-1597.
MEDLINE
20.
Bos AJ, van der Stap CC, Valkovic V, Vis RD, Verheul H.
Incorporation routes of elements into human hair; implications for hair
analysis used for monitoring.
Sci Total Environ.
1985;42:157-169.
MEDLINE
21.
Yukawa M, Suzuki-Yasumoto M, Tanaka S.
The variation of trace element concentration in human hair: the trace
element profile in human long hair by sectional analysis using neutron
activation analysis.
Sci Total Environ.
1984;38:41-54.
MEDLINE
22.
Hambridge KM.
Hair analysis worthless for vitamins, limited for minerals.
Am J Clin Nutr.
1982;36:943-949.
MEDLINE
23.
DuPont RL, Baumgartner WA.
Drug testing by urine and hair analysis: complementary features and
scientific issues.
Forensic Sci Int.
1995;70:63-76.
MEDLINE
24.
Klevay LM, Bistrian BR, Fleming CR, Neumann CG.
Hair analysis in clinical and experimental medicine.
Am J Clin Nutr.
1987;46:233-236.
MEDLINE
25.
Hair Analysis: A Potential for Abuse.
Chicago, Ill: American Medical Association; 1994. Policy No. H-175.995.