Variability in urinary oxalate measurements between six international laboratories.

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Serval ID
serval:BIB_88B11FF5FAE6
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Variability in urinary oxalate measurements between six international laboratories.
Journal
Nephrology, Dialysis, Transplantation
Author(s)
Maalouf N.M., Adams Huet B., Pasch A., Lieske J.C., Asplin J.R., Siener R., Hesse A., Nuoffer J.M., Frey F.J., Knight J., Holmes R.P., Zerwekh J.E., Bonny O.
ISSN
1460-2385 (Electronic)
ISSN-L
0931-0509
Publication state
Published
Issued date
2011
Volume
26
Number
12
Pages
3954-3959
Language
english
Notes
Publication types: Comparative Study ; Journal Article ; Multicenter Study ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Abstract
BACKGROUND: Hyperoxaluria is a major risk factor for kidney stone formation. Although urinary oxalate measurement is part of all basic stone risk assessment, there is no standardized method for this measurement.
METHODS: Urine samples from 24-h urine collection covering a broad range of oxalate concentrations were aliquoted and sent, in duplicates, to six blinded international laboratories for oxalate, sodium and creatinine measurement. In a second set of experiments, ten pairs of native urine and urine spiked with 10 mg/L of oxalate were sent for oxalate measurement. Three laboratories used a commercially available oxalate oxidase kit, two laboratories used a high-performance liquid chromatography (HPLC)-based method and one laboratory used both methods.
RESULTS: Intra-laboratory reliability for oxalate measurement expressed as intraclass correlation coefficient (ICC) varied between 0.808 [95% confidence interval (CI): 0.427-0.948] and 0.998 (95% CI: 0.994-1.000), with lower values for HPLC-based methods. Acidification of urine samples prior to analysis led to significantly higher oxalate concentrations. ICC for inter-laboratory reliability varied between 0.745 (95% CI: 0.468-0.890) and 0.986 (95% CI: 0.967-0.995). Recovery of the 10 mg/L oxalate-spiked samples varied between 8.7 ± 2.3 and 10.7 ± 0.5 mg/L. Overall, HPLC-based methods showed more variability compared to the oxalate oxidase kit-based methods.
CONCLUSIONS: Significant variability was noted in the quantification of urinary oxalate concentration by different laboratories, which may partially explain the differences of hyperoxaluria prevalence reported in the literature. Our data stress the need for a standardization of the method of oxalate measurement.
Keywords
Clinical Laboratory Techniques/standards, Humans, International Cooperation, Laboratories, Oxalates/urine, Reproducibility of Results
Pubmed
Web of science
Open Access
Yes
Create date
13/02/2013 18:06
Last modification date
20/10/2020 11:12
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