Should kidney tubular markers be adjusted for urine creatinine? The example of urinary cystatin C

Abstract

We recommend using the uCST3 value to evaluate the extent of renal tubular damage. Indeed, our conflicting results on uCST3/uCreat can be extended to every marker of tubular function. Evaluating a urine marker specific for renal tubular damage to a second urine marker that is itself strongly dependent upon glomerular or other renal or non-renal conditions, impairs its clinical relevance and may lead to incorrect interpretations. Correction with uCreat can be performed only in pure glomerulopathy, when specific markers of glomerular function are measured (i.e., urinary albumin). In all other cases of renal diseases, such correction is inappropriate and should be avoided. Clin Chem Lab Med 2009;47:1553-6.

Assessment of Urinary Betaine as a Marker of Diabetes Mellitus in Cardiovascular Patients

“…Details on randomization and the vitamin regimen have been published elsewhere [16]. Because urinary creatinine levels are increased by tubular secretion in renal failure [17], [18], patients (n = 54) with estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m 2 or macroalbuminuria (urinary albumin/creatinine ratio (UACR) >30 mg/mmol) were excluded from the present study.…”

Cystatin C and collagen type IV in diagnostics of chronic kidney disease in type 2 diabetic patients

“…Концентрацию цистатина С в моче определяли иммунотурбидиметрическим методом на анализаторе Abbott Architect c8000 с помощью наборов реагентов Cystatin C-AT фирмы Alfresa Pharma Corporation (Япо-ния). Учитывая, что введение поправки на креатинин, за-висимый от канальцевой реабсорбции и секреции, может ухудшать диагностическую ценность исследования экс-креции цистатина С [13], концентрацию цистатина С в моче оценивали без пересчета на креатинин.…”

Proteo‐Metabolomic Strategies in the Future of Drug Development

“…It has been common to base normalization on creatinine concentrations in urine [294]. This may be correct as long as creatinine clearance is normal.…”

“…However, the urine creatinine concentration is a function of glomerular filtration, tubular excretion, gender, and age and may be affected by creatinine release from other sources such as muscle. Adjustment of urinary molecular marker concentrations based on urinary creatinine in patients with disease processes or drug effects that affect release and handling of creatinine by the kidney will give misleading results [294]. Likewise, in 1 H-NMR-based metabolomics studies, scaling based on the overall integral represents the standard approach [295][296][297].…”

“…Especially strong metabonomic changes, evident as massive amounts of single metabolites in samples, significantly hamper the integral normalization resulting in incorrectly scaled spectra. Normalization based on urinary cystatin C concentrations [294] has been proposed for clinical samples. In the case of 1 H-NMR-based metabolite profiles, probabilistic quotient normalization was found to work best [295].…”