Biological Variation of Creatinine, Cystatin C, and eGFR over 24 Hours

Judith M. Hilderink, Noreen van der Linden, Dorien M. Kimenai, Elisabeth J. R. Litjens, Lieke J. J. Klinkenberg, Breshna M. Aref, Fahra Aziz, Jeroen P. Kooman, Roger J. M. W. Rennenberg, Otto Bekers, Richard P. Koopmans, Steven J. R. Meex*

*Corresponding author for this work

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Abstract

BACKGROUND: Estimated glomerular filtration rate (eGFR) is widely used in clinical practice. This study assessed the within-subject biological variation (CVI) of different eGFR equations in people with chronic kidney disease (CKD) and people without CKD. The aims of this study were (a) to determine the 24-h biological variation profiles of creatinine, cystatin C, and eGFR and (b) to determine whether CVI of creatinine, cystatin C, and eGFR changes on deterioration of glomerular filtration.

METHODS: Hourly blood samples were analyzed from 37 individuals (17 without CKD, 20 with CKD) during 24 h. Creatinine (enzymatic method) and cystatin C were measured using a Cobas 8000 (Roche Diagnostics). eGFR was estimated using the Modification of Diet in Renal Disease and the Chronic Kidney Disease Epidemiology Collaboration based on creatinine and/or cystatin C. Plasma samples were stored at similar to 80 degrees C before analysis. Outlier and homogeneity analyses were checked before performing a nested ANOVA to determine biological variation.

RESULTS: CVI of creatinine was higher in people without CKD than in those with CKD (6.4% vs 2.5%) owing primarily to the more profound effect of meat consumption on creatinine variability in individuals with lower baseline creatinine concentrations. Unlike creatinine, cystatin C concentrations were unaffected by meat consumption. Cystatin C showed some diurnal rhythmic variation and less in people with CKD. Reference change values (RCVs) of all eGFR equations were within 13% to 20% in both study groups.

CONCLUSIONS: Despite differences in CVI of creatinine, the CVI and RCV of the eGFR equations were relatively similar for people with or without CKD. (c) 2018 American Association for Clinical Chemistry

Original languageEnglish
Pages (from-to)851-860
Number of pages10
JournalClinical Chemistry
Volume64
Issue number5
DOIs
Publication statusPublished - May 2018

Keywords

  • GLOMERULAR-FILTRATION-RATE
  • CHRONIC KIDNEY-DISEASE
  • CARDIAC TROPONIN-T
  • COOKED-MEAT MEAL
  • SERUM CREATININE
  • CLINICAL-CHEMISTRY
  • CRITICAL-APPRAISAL
  • INDIVIDUALS
  • VARIABILITY
  • ANALYTES

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