bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computerized method for validating laboratory reference ranges for triiodothyronine and thyroxin immunoassays
Authors: Luttrell Brian , Watters Sall 
Published: January 2020

Abstract
We used a computer-based method to help validate the reference ranges of assays for triiodothyronine (T3) and thyroxin (T4). A retrospective search of a database of laboratory results for the previous six months identified all patients with apparent euthyroid status, as defined by methods independent of the immunoassay under review. A computer-generated reference group (CGR Group) of 2001 records had a gaussian distribution of T4 values and a reference range (mean +/- 2 SD) of 56-161 nmol/L, compared with the supplier's suggested range for euthyroid subjects (58-148 nmol/L) and an in-house range of 60-144 nmol/L for a group of 97 normal subjects. A similar CGR Group of 1902 records gave a reference range for T3 of 0.7-2.1 nmol/L (manufacturer's range 0.8-2.8; normal subjects 0.8-2.2). An attempt to devise a reference range for thyrotropin failed when we found that its concentration in the population of patients with normal values for thyroid hormones was distributed differently from that in the normal population. The method is intended to be used in addition to conventionally derived ranges based on results for healthy subjects. It allows the laboratory to conveniently verify the reference ranges for T3 and T4 assays at regular intervals by using very large samples with appropriate age, sex, and weight distribution, drawn from the population of patients' samples submitted for analysis.
Lipase activity in serum measured with Ektachem is often increased in nonpancreatic disorders
Authors: Tetrault Gregory A 
Published: January 2020

Abstract
For patients with symptoms of pancreatitis, measurement of amylase in serum reportedly is more sensitive than that of lipase in acute pancreatitis, whereas lipase reportedly is more specific. However, serum lipase activities exceeding the upper reference limit (URL) have been reported for many patients who did not have pancreatitis. I reviewed the serum lipase and amylase concentrations of 493 consecutive inpatients and emergency department patients for whom both tests were ordered. Serum lipase and amylase activities, determined with an Ektachem 700 analyzer, were less than or equal to URL for 390 patients (83%) and greater than URL for 103. Medical records of 101 of these 103 were reviewed; 18 had acute or chronic relapsing pancreatitis. In this latter group, serum lipase values greater than URL had 100% sensitivity and 84% specificity; those of serum amylase greater than URL had 72% sensitivity and 88% specificity. However, the test combination of serum lipase greater than URL and serum amylase less than or equal to URL also occurred in 84% of the patients in which review of the medical records revealed nonpancreatic gastrointestinal or hepatobiliary disorders as the primary problem (n = 55). Therefore, serum lipase activity measured with the Ektachem assay is also often increased in patients with intra-abdominal disorders that appear to be nonpancreatic.
Health care in the developing world: need for appropriate laboratory technology
Authors: Heuck Claus C , Deom Andrȳ 
Published: January 2020

Abstract
Health care technology is rapidly advancing, and the development of equipment based on new principles has had a strong impact on laboratory services in Western countries. The use of such technologies frequently creates problems in countries of the Third World, because the effects of several interacting elements are not always taken into account. Not only technical factors but also socioeconomic and political factors, as well as differences in diseases in developing countries, must be considered. Standardization of equipment and methodology, and adaptation to local health systems, will facilitate improvement of laboratory services. Training and incentives for local initiatives are fundamental elements for the provision of cost-effective health care.
Development, validation, and certification by isotope dilution gas chromatography-mass spectrometry of lyophilized human serum reference materials for cortisol (CRM 192 and 193) and progesterone (CRM 347 and 348)
Authors: Thienpont Linda , Siekmann Lothar , Lawson Alexander , Colinet Elisabeth , De Leenheer Andrȳ 
Published: January 2020

Abstract
The Community Bureau of Reference of the European Communities has produced four batches of lyophilized serum Certified Reference Materials, two for cortisol (CRM 192 and 193) and two for progesterone (CRM 347 and 348). For cortisol, one of the pools consisted of serum from healthy blood donors, whereas the second batch was supplemented with pure cortisol. The progesterone Reference Materials contained only endogenous hormone concentrations. Assessment of vial-to-vial variability in the cortisol and progesterone concentrations showed no between-sample inhomogeneity, and the materials were stable. The quality of the materials was therefore considered sufficient for certification of the values for the cortisol and progesterone concentrations by a collaborative study involving several laboratories from the European Communities, using isotope dilution gas chromatography-mass spectrometry. Inaccuracy in reconstitution of the lyophilized materials was less than 0.3%; imprecision of sampling was less than 0.2%. For determinations of cortisol and progesterone concentrations, the mean within-laboratory coefficients of variation (CVs) were 1.76% (CRM 192), 1.19% (CRM 193), 1.64% (CRM 347), and 1.75% (CRM 348). The between-laboratory CVs were greater: CRM 192, 1.79%; CRM 193, 1.48%; CRM 347, 2.08%; and CRM 348, 2.16%. The concentrations in the reconstituted Reference Materials were certified to be 273 nmol/L in CRM 192 and 763 nmol/L in CRM 193 for cortisol and 10.13 nmol/L in CRM 347 and 40.3 nmol/L in CRM 348 for progesterone. Uncertainties at the 0.95 confidence level--6 (CRM 192), 14 (CRM 193), 0.21 (CRM 347), and 1.0 nmol/L (CRM 348)--were considered compatible with the intended use of the materials.
Comparison of four methods for free thyroxin
Authors: Deam D , Goodwin M , Ratnaike S 
Published: January 2020

Abstract
We performed a limited evaluation of four free thyroxin (FT4) reagent kits: the Amerlex-M (AFT4), the Amerlite (LFT4), the MagicLite (MFT4), and the GammaCoat two-step RIA (GFT4). FT4 was measured in specimens from 201 subjects: 19 healthy controls, 14 patients who were thyrotoxic, 13 who were hypothyroid, 59 who had a past history of thyroid disease, seven with thyroxin autoantibodies, seven who were taking amiodarone, and 82 who had no clinical indication of thyroid hormone abnormality. Of these 201 subjects, 78 had a low serum albumin (less than 35 g/L) and 27 had severe nonthyroidal illness. We also investigated 60 pregnant subjects. We found no correlation between thyroxin-binding globulin (TBG) and FT4 in any of the assays, and only the AFT4 method showed a significant correlation with albumin concentrations. The presence of autoantibodies to thyroxin affected the results of all methods except the GFT4 method. All methods showed a decrease in mean FT4 values in late pregnancy. Correlation of patients' clinical state and FT4 results suggested that the reference ranges published by the manufacturers need to be modified for our laboratory.
IgA anti-gliadin antibodies in adult celiac disease
Authors: Hill P G , Thompson S P , Holmes G K 
Published: January 2020

Abstract
We have improved the enzyme-linked immunosorbent assay for IgA-class antibodies to gliadin in serum by evaluating earlier publications. We also assess the value of measuring these antibodies when screening for adult celiac disease and monitoring dietary compliance. Of 61 adults with untreated celiac disease, 57 had abnormal results, giving a sensitivity for the test of 0.93. Patients (n = 283) attending a gastroenterology clinic formed the control group. The predictive values of positive results and negative results were 50% and 99.7%, respectively, indicating that the test has a role in helping select those subjects in whom small bowel biopsy is indicated. Adults with celiac disease, after two years on a strict gluten-free diet, and normal subjects showed no significant difference in serum IgA-class anti-gliadin antibody concentrations. The test thus provides objective evidence of dietary compliance in addition to its role as a screening test.
Simple enzyme immunoassay for the simultaneous measurement of whole choriogonadotropin molecules and free beta-subunits in sera of women with abnormal pregnancies or tumors of the reproductive system
Authors: Choi M J , Choe I S , Kang H K , Lee J S , Chung T W 
Published: January 2020

Abstract
A multiple enzyme immunoassay (multi-EIA) was developed to quantify whole-molecule human choriogonadotropin (w-hCG) and free hCG beta-subunits (hCG-beta) simultaneously. A clone of a specific monoclonal antibody was coupled to solid phase; two other clones of different monoclonal antibodies were conjugated to horseradish peroxidase (HRP; EC 1.11.1.7) and alkaline phosphatase (AP; EC 3.1.3.1), respectively. These two enzyme conjugates were mixed together to measure w-hCG or hCG-beta, depending on the selection of the enzyme substrate. To measure w-hCG and hCG-beta simultaneously, both enzyme substrates were used with the blended enzyme conjugates. The assay is simple and reproducible, and can be completed within 2 h with high specificity and sensitivity. We measured w-hCG and hCG-beta in the sera of women with abnormal pregnancies and in patients with tumors of the reproductive system, and observed different hCG-beta/w-hCG ratios in patients with various types of trophoblastic tumors.
Interferences in current methods for measurements of creatinine
Authors: Weber J A , van Zanten A P 
Published: January 2020

Abstract
We measured the interference of carbonyl compounds, drugs, and other substances in human serum on the determination of creatinine by the two-point, fixed-time kinetic modification of the Jaffé reaction as well as by four enzymatic methods. We added known concentrations of the interfering substances to a solution of creatinine in water. For bilirubin, we used both pooled normal sera with added bilirubin and icteric patient sera. The magnitude of interferences varies widely from method to method. Carbonyl compounds, dopamine, cephalosporines, and bilirubin interfere with the Jaffé reaction. Bilirubin, creatine, dopamine, ascorbic acid, and sarcosine interfere with the enzymatic methods. We conclude that the elimination of interferences in the determination of creatinine has still not been achieved.
Evaluation of an assay of the free beta-subunit of choriogonadotropin and its potential value in screening for Down's syndrome
Authors: Spencer Kevin 
Published: January 2020

Abstract
In this study I investigated the analytical and clinical performance of the measurement of the free beta-subunit of choriogonadotropin (hCG) in normal pregnancies and in pregnancies affected by Down's syndrome. Free beta-hCG in maternal serum has been shown to be increased in Down's syndrome-affected pregnancies and is proportionally increased in more cases than is total hCG. This study confirms previous findings of low concentrations of unconjugated estriol and alpha-fetoprotein in maternal serum in Down's syndrome-affected pregnancies. Using a multivariate risk analysis of maternal age and concentrations of alpha-fetoprotein, unconjugated estriol, and hCG in maternal serum, I determined that, at a risk cutoff value of 1 in 300, 52% of Down's cases could be detected with total hCG in the calculation, compared with 66% with the free beta-hCG concentration. The false-positive rate was 5.9% in both cases. Therefore, free beta-hCG can be used effectively in a screening program for Down's syndrome; however, further studies are required to ascertain whether the measurement of free beta-hCG has any advantages over the use of total hCG for detecting Down's syndrome.
Multiple forms of alkaline phosphatase in plasma of hemodialysis patients
Authors: Tibi L , Chhabra S C , Sweeting V M , Winney R J , Smith A F 
Published: January 2020

Abstract
We used quantitative assays to measure the activity of the bone, liver, and intestinal forms of alkaline phosphatase in plasma in 75 patients with endstage chronic renal failure undergoing hemodialysis. The results were correlated with radiological and other biochemical indices of bone disease and with biochemical indices of liver disease. The total activity of alkaline phosphatase in plasma increased in 28 patients. In 10 of these patients, nine of whom had increased activity of gamma-glutamyltransferase in plasma, the increase in total activity of alkaline phosphatase was from the liver isoenzyme alone (nine patients) or from the liver and bone isoenzymes together (one patient). Intestinal alkaline phosphatase in plasma, although greater than 23 U/L in eight patients, was solely responsible for the increase in total alkaline phosphatase in one patient (who had normal gamma-glutamyltransferase). Bone alkaline phosphatase in plasma was increased in 25 patients, seven of whom had normal total alkaline phosphatase, and was closely correlated (r = 0.78) with osteocalcin concentration in plasma, which was increased in a much greater proportion of patients (99%). Both total and bone alkaline phosphatase were correlated with parathyrin in plasma (r = 0.46 and 0.50, respectively) and with osteocalcin (r = 0.60 and 0.78, respectively). Osteocalcin and bone alkaline phosphatase, but not parathyrin, decreased with age, implying that the skeletal response to parathyrin may be age dependent. In patients with increased total alkaline phosphatase undergoing hemodialysis, the concurrent measurement of gamma-glutamyltransferase may help identify whether the enzyme increase originates from the liver or bone, but this approach wrongly identified the source of the increase in three of 28 patients. Therefore, we recommend a separate measurement of the bone isoenzyme of alkaline phosphatase.
Assessing acute parathyroid responsiveness in hemodialysis patients by measuring intact parathyrin in pre- and post-dialysis serum
Authors: Dilena Beverly A , White Graham H 
Published: January 2020

Abstract
We measured pre- and post-dialysis concentrations of ionized calcium (iCa) in whole blood, total calcium (tCa) in plasma, and intact parathyrin (PTH) in serum of 19 patients undergoing maintenance hemodialysis. Plasma tCa was inappropriately increased relative to iCa in 63% of the specimens; the iCa correlated with the PTH concentration in 12 of 19 pre-dialysis specimens, whereas tCa correlated with PTH in only five patients. During dialysis, 16 patients had analytically significant changes in iCa (i.e., exceeded the analytical imprecision of 0.04 mmol/L). Pre- and post-dialysis concentrations of PTH were normal in six patients, four of whom showed a detectable response to changes in iCa. Ten patients had increased PTH in at least one specimen; of these, eight had responsive parathyroid glands. Five of the 16 patients had an increased set point for calcium. The minimal PTH responses of two patients suggested refractory hyperparathyroidism. We conclude that routine estimation of iCa, rather than tCa, in dialysis patients markedly improves the identification of patients at risk for secondary hyperparathyroidism, and that measurement of intact PTH in pre- and post-dialysis serum offers a simple means of assessing parathyroid responsiveness in dialysis patients.
One-step chromogenic equivalent of activated partial thromboplastin time evaluated for clinical application
Authors: Ponjee Gabriëlle E , Vader Huib L , de Wild Net J , Janssen Ger W T , van der Graaf Fedde 
Published: January 2020

Abstract
We evaluated the clinical usefulness of a recently developed semi-automated one-step chromogenic equivalent of activated partial thromboplastin time (APTT; Behring). This simple test is easily adaptable for automation. Generally, the results with this chromogenic one-step APTT were at least as precise as those obtained with comparative coagulometric methods. The chromogenic one-step APTT showed, both in vitro and in vivo, adequate sensitivity to congenital intrinsic factor deficiency but no sensitivity to Factor VII deficiency. Unlike a two-step coagulometric APTT (Dade), the one-step chromogenic APTT seemed sensitive to activation products of the contact system, which are present in immunoadsorbed factor-deficient plasma. The in vitro sensitivity of the chromogenic APTT to heparin was comparable with that of a coagulometric APTT, but the sensitivity to heparin in patients' samples differed slightly. The chromogenic APTT is relatively insensitive to anomalies in the fibrinogen-fibrin conversion. Finally, we observed discrepancies between the chromogenic and coagulometric APTT results for plasma of patients with disseminated intravascular coagulation. We conclude that this one-step chromogenic APTT warrants further evaluation for possible use as a routine test for the clinical laboratory.
Clinical validation of a second-generation fructosamine assay
Authors: Cefalu William T , Bell-Farrow Audrey D , Petty Marie , Izlar Camille , Smith Jeffrey A 
Published: January 2020

Abstract
The serum fructosamine assay, used to monitor short-term clinical glycemic control, reportedly has several technical drawbacks. However, technical improvements have resulted in a new second-generation assay of fructosamine. We evaluated this second-generation assay (from Roche Diagnostics) in 529 nondiabetic and diabetic patients and found a highly significant correlation with results of the first-generation assay (r = 0.91, P less than 0.001). Use of the second-generation assay with samples from patients classified on the basis of glycemic control according to their glycohemoglobin (GHb) values, enabled us to discriminate between the nondiabetics, diabetics with "good/moderate" control (i.e., GHb less than 10%), and diabetics with "poor" control (GHb greater than or equal to 10%). We evaluated the validity of the second-generation assay to assess short-term glycemic control in 23 non-insulin-dependent diabetic patients who participated for 10 weeks in an intensive intervention program designed to rapidly normalize the clinical glycemic profile. Results correlated significantly with the one-week average capillary blood glucose concentration (CBG) and with the three-week average CBG in all 23 patients. In addition, the second-generation fructosamine assay results demonstrated a significant decrease at each week of study, as did the average CBG. Results of the first- and second-generation assays correlated significantly at each week of study. GHb correlated significantly with both the second- (r = 0.78, P less than 0.001) and first-generation fructosamine assay results (r = 0.77, P less than 0.001) for the baseline blood samples of the intervention study, but this correlation decreased (to r = 0.35, P = 0.09 and r = 0.34, P = 0.09, respectively) by the conclusion of the study.
Multicenter evaluation of new enzyme-linked immunoassays of follitropin and lutropin in serum or plasma
Authors: Thijssen J H , Wood W G , Kessler A C , Griesser H W , Bauer O , Bieglmayer C , Eugui J , Mirabel J L , Gaessler H , Klinga K 
Published: January 2020

Abstract
Results from a multicenter evaluation of two new enzyme-linked immunosorbent assays [Enzymun-Test for follitropin (FSH) and lutropin (LH)] are presented and compared with results from 11 other commercial immunoassays, radioactive as well as nonradioactive. Enzymun-Test FSH and LH assays are suitable for automated systems and manual applications. The tests were reproducible (CV less than 5%), highly specific, and sensitive enough (less than 0.5 int. unit/L) to measure the hormones directly in almost all patients' samples, except for LH measurements in prepubertal children. We did not find interference by heterophilic antibodies or other factors. A comparison of assays for FSH found very good agreement among all modern two-site assays; competitive immunoassays almost invariably yielded systematically lower results for FSH, probably because of the heterogeneity of the International Reference Preparation (2nd IRP FSH, 78/549). For LH also we found good agreement, with no systematic differences among the various reagents. Guidelines for reference values with the new reagents are given.
Automated measurement of amylase isoenzymes by a double kinetic assay with "blocked" beta-2-chloro-4-nitrophenyl maltopentaoside as substrate and with wheat germ inhibitor
Authors: Abe A , Nishimura T , Noma A , Hamano K 
Published: January 2020

Abstract
We evaluated the enzymic mechanism by which 3-keto butylidene-beta-2-chloro-4-nitrophenyl maltopentaoside (3KB-G5-CNP) serves as a substrate for serum pancreatic (p-) and salivary (s-) amylases. In aliquots of the reaction mixture, three kinds of beta-2-chloro-4-nitrophenyl oligosaccharides (glucose, maltoside, and maltotrioside) were separated from the substrate by high-performance liquid chromatography. Both isoenzymes behaved nearly identically and produced almost the same products. We automated a double kinetic procedure for determining total (t-) and p-amylase with use of a selective inhibitor from wheat germ in a single channel on the Hitachi 7050 analyzer. Within- and between-run CVs were, respectively, 0.5% and 1.7% for t-amylase (240 U/L), and 0.7% and 2.3% for p-amylase (230 U/L). The test results varied linearly with concentrations up to approximately 2000 U/L for t- and p-amylase activities. p/s ratios varied from 0.2 to 5.0. Results correlated well with those obtained by the monoclonal inhibition method (r = 0.992).
Interference in thyroid-function tests in postpartum thyroiditis
Authors: John R , Othman S , Parkes A B , Lazarus J H , Hall R 
Published: January 2020

Abstract
Three women are described from a study of patients with postpartum thyroiditis whose sera gave spuriously increased concentrations of free thyroid hormone because of antibody binding of radiolabeled thyroxin (T4) and triiodothyronine (T3) analogs. All of the women showed increased serum concentrations of thyroid autoantibodies. The antibody binding of radiolabeled analogs and its effect on free T4 and free T3 assays disappeared by 48 weeks postpartum. Postpartum women who develop thyroid autoantibodies have approximately 2% prevalence of increased binding of radiolabeled analogs, which can result in an interference in thyroid hormone assays involving T4 and T3 analogs.
S-troponin T in suspected ischemic myocardial injury compared with mass and catalytic concentrations of S-creatine kinase isoenzyme MB
Authors: Gerhardt W , Katus H , Ravkilde J , Hamm C , Jørgensen P J , Peheim E , Ljungdahl L , Löfdahl P 
Published: January 2020

Abstract
In a multicenter study we compared three tests for ischemic myocardial injury (IMI): a new, automated enzyme immunoassay for S-troponin T (S-TNT; Boehringer Mannheim) and two S-creatine kinase (CK) isoenzyme MB assays (mass and catalytic concentrations). For critical evaluation of clinical sensitivity, we studied 243 cases with an IMI prevalence of 43% and an 18% prevalence of cases with unstable angina. Relative peak values of S-TNT and S-CK-MB (mass) after onset of pain were four- to fivefold higher than S-CK-MB (catalytic) results. Increases of S-TNT and S-CK-MB (mass), even though still within their reference ranges, indicated minor myocardial damage in about one-third of the cases primarily classified as unstable angina. The diagnostic window for S-TNT ranged from hours to weeks after the acute episode. The time courses were frequently biphasic, with the initial S-TNT peak closely paralleling that of the mass concentrations of S-CK-MB. With a biological half-life for S-TNT of 2 h, the prolonged increases in S-TNT indicate a continuous release of S-TNT from necrotizing cells. Clinical specificities of S-TNT and S-CK-MB (mass) were greater than that of S-CK-MB (catalytic), even in the presence of 30% to 40% severe skeletal muscle injuries. The combination of S-TNT and S-CK-MB (mass) is excellent for detection of acute IMI, including minor myocardial damage.