Desirable Performance Standards for Clinical Chemistry Tests

Cg, Fraser

doi:10.1016/s0065-2423(08)60403-5

Cited by 111 publications

(39 citation statements)

References 89 publications

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“…The assay variation (CV) was relatively high but still within the range of acceptability. Because the urine albumin excretion rate can vary highly (by up to 40%) from day to day (36 ), an analytical CV equal to or less than one-half of the intraindividual biological variation (Ͻ18%) would be considered as desirable performance (37 ). In practical settings, the dry-reagent assay will be fully automated, which will help reduce the assay variation observed here.…”

Section: Discussionmentioning

confidence: 99%

Time-resolved Fluorescence Resonance Energy Transfer Assay for Point-of-Care Testing of Urinary Albumin

2003

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Background:Microalbuminuria is an established early marker of diabetic nephropathy and an important cardiovascular risk factor in diabetes and hypertension. We aimed to develop a rapid point-of-care assay for the measurement of urine albumin. Methods: The competitive homogeneous assay used an albumin-specific monoclonal antibody labeled with a stable fluorescent europium chelate as donor and an albumin labeled with cyanine 5 (Cy5) as acceptor. The assay was performed at room temperature in single microtitration wells that contained all the required dryform reagents. The close proximity between the two labels in the immune complex allowed fluorescence resonance energy to be transferred from the pulseexcited europium chelate to the acceptor Cy5. The emission of long-lived energy transfer signal from the sensitized Cy5 was measured at 665 nm with time-resolved fluorometry that eliminated short-lived background. Results: The assay procedure required 12 min for a 10-L urine sample. The working range was from 10 to ϳ320 mg/L, and the lower limit of detection was 5.5 mg/L. The within-and between-run CVs were 6.9 -10% and 7.5-13%, respectively. Recovery was 103-122%. The assay correlated well (r 2 ‫؍‬ 0.98; n ‫؍‬ 37) with a laboratory-based immunoassay, although mean (SD) results were 7 (29)% lower. Conclusions: The speed and ease of performance of this assay recommend it for near-patient use. The assay is the first to combine a fluorescence resonance energy transfer-type rapid competitive assay with an all-in-one dry reagent.

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Section: Discussionmentioning

confidence: 99%

Time-resolved Fluorescence Resonance Energy Transfer Assay for Point-of-Care Testing of Urinary Albumin

2003

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“…This CV is more than 1/2 of the intraindividual biological variation (7.4%), which is a widely stated goal for analytical methods. 10 Automation of sample and reagent dispensing should improve the analytical precision. One limitation of this assay is that the solubility of the Table 2.…”

Section: Discussionmentioning

confidence: 99%

Bovine Plasma β-Mannosidase Activity and Its Potential use for β-Mannosidosis Carrier Detection

et al. 1992

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Abstract. Plasma ß-mannosidase activities were determined for Salers cattle from 8 herds as an evaluation of this method for detection of ß-mannosidosis heterozygotes. Several biological factors, such as age, gender, herd, and risk of being a ß-mannosidosis carrier, were considered in this study. The mean enzyme activity for obligate heterozygotes (n = 8) was 55 U/ml (range = 43-65 U/ml), which was 59% of the mean enzyme activity for cattle that were low risk for being a carrier. These data indicate that bovine ß-mannosidosis is characterized by a gene dosage effect. The analytical and biological variation of plasma ß-mannosidase activity that was observed necessitates limiting the test to adult fullblood/purebred Salers cattle within a herd. Plasma ß-mannosidase analysis provides important information for intraherd selection of Salers cattle that are heterozygous for ß-mannosidosis. ß-mannosidosis is an autosomal recessive defect of glycoprotein catabolism that has been reported in goats, 11,18,19 human 5,6,7,21,28 and, most recently, Salers cattle [1][2][3]13,25 From birth, affected Salers calves are unable to rise and have a characteristic appearance consisting of a slightly domed head, slight protrusion of the lower jaw, narrow eye openings, and abundant purplish gums. Handling of these calves reveals skin that seems tightly adhered to the body. The calves cannot stand even with assistance, and during periods of sternal recumbency they make wide circular head movements often combined with bobbing movements. These combined uncontrolled movements usually propel the calf into lateral recumbency. Affected calves cannot seek their mother to nurse, and even if milk/colostrum is offered (via a bottle) they are unable to suckle effectively. The disease is rapidly fatal in newborn ruminants. 1,17 Human ß-mannosidosis is clinically heterogeneous. Mental retardation and deafness are the most characteristic features. 6,7,21,28 Birth of affected calves has been reported in at least 4 states in the United States as well as in Canada and New Zealand. The American Salers Association has estimated that of 20,000 calves born in 1990, approximately 10 calves were positively diagnosed as having ß-mannosidosis. However, a true estimation of the gene frequency is not possible because the disease has only recently been described, and it may be confused with hydrocephalus or bovine viral diarrhea infection. Furthermore, reporting of bovine ß-mannosidosis is voluntary and breeders may be reluctant to report these cases for economically important livestock.The biochemical hallmark of this neurovisceral storage disease is the absence of plasma ß-mannosidase activity. In caprine and bovine ß-mannosidosis, Manß1-4G1cNAc and Marßl-4G1cNAcßl-4G1cNAc as well as more complex oligosaccharides accumulate in tissues and urine. 1,17,19,20,[22][23][24] The Manßl-4G1cNAc disaccharide is the main uncatabolized substrate in humans. 6,7,21,28 The disease is clinically and biochemically quite different from α−mannosidosis that is described in Angus,...

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“…It is widely accepted that analytical goals, the standards of analytical performance required to provide optimal patient care, are best derived from data on biological variation (11). Goals for imprecision were derived as 1/2CVI (2).…”

Section: Analytical Goalsmentioning

confidence: 99%

Biological Variation in Protein C, Protein S and Antithrombin Concentrations in Plasma of Healthy Subjects

d’Eril¹,

Anesi²,

Rizzo³

et al. 1997

Clinical Chemistry and Laboratory Medicine

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Summary:The analytical, intra-and inter-individual components of biological variation were estimated for protein C, protein S and antithrombin over a period of 6 weeks in a cohort of 17 apparently healthy subjects. Expressed as percentage activity (protein C and antithrombin) and as percentage concentration in normal human plasma (protein S), the mean values for men and women show no significant differences (p > 0.05) for any of the analytes studied. Calculated analytical goals (CV, %) for precision required for optimal patient care are: protein C, 2.9; protein S, 2.9 and antithrombin 2.7. A single numerical index, called "index of fiduciality", was also calculated to demonstrate that the analytical performance of our method was satisfactory. The generally applicable differences (% activity or % concentration) required for two results to be significantly different (p ^ 0.05) were calculated as: protein C, 17; protein S, 16 and antithrombin, 16. The usefulness of critical differences as guidelines for the interpretation of changes in serial results was investigated using an "index of heterogeneity" of intra-individual variation.The marked degree of individuality demonstrated for all the quantities indicates that, if conventional populationbased ranges are used uncritically, major changes in analyte concentration may not be correctly identified for some patients, because observed values continue to lie within the reference range. The utility of conventional populationbased reference intervals was determined by calculating a single numerical index, called "index of individuality". For protein C, protein S and antithrombin we found that five of a patient's specimens are required to achieve a 95% chance that the mean is within ± 5% of the true value.

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Desirable Performance Standards for Clinical Chemistry Tests

Cited by 111 publications

References 89 publications

Time-resolved Fluorescence Resonance Energy Transfer Assay for Point-of-Care Testing of Urinary Albumin

Time-resolved Fluorescence Resonance Energy Transfer Assay for Point-of-Care Testing of Urinary Albumin

Bovine Plasma β-Mannosidase Activity and Its Potential use for β-Mannosidosis Carrier Detection

Biological Variation in Protein C, Protein S and Antithrombin Concentrations in Plasma of Healthy Subjects

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