Factors other than glomerular filtration rate affect serum cystatin C levels

Kidney Int. 2009 Mar;75(6):652-60. doi: 10.1038/ki.2008.638. Epub 2008 Dec 31.

Abstract

Cystatin C is an endogenous glomerular filtration marker hence its serum level is affected by the glomerular filtration rate (GFR). To study what other factors might affect it blood level we performed a cross-sectional analysis of 3418 patients which included a pooled dataset of clinical trial participants and a clinical population with chronic kidney disease. The serum cystatin C and creatinine levels were related to clinical and biochemical parameters and errors-in-variables models were used to account for errors in GFR measurements. The GFR was measured as the urinary clearance of 125I-iothalamate and 51Cr-EDTA. Cystatin C was determined at a single laboratory while creatinine was standardized to reference methods and these were 2.1+/-1.1 mg/dL and 1.8+/-0.8 mg/L, respectively. After adjustment for GFR, cystatin C was 4.3% lower for every 20 years of age, 9.2% lower for female gender but only 1.9% lower in blacks. Diabetes was associated with 8.5% higher levels of cystatin C and 3.9% lower levels of creatinine. Higher C-reactive protein and white blood cell count and lower serum albumin were associated with higher levels of cystatin C and lower levels of creatinine. Adjustment for age, gender and race had a greater effect on the association of factors with creatinine than cystatin C. Hence, we found that cystatin C is affected by factors other than GFR which should be considered when the GFR is estimated using serum levels of cystatin C.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Age Factors
  • Continental Population Groups
  • Creatinine / blood*
  • Cross-Sectional Studies
  • Cystatin C / blood*
  • Female
  • Glomerular Filtration Rate*
  • Humans
  • Kidney Function Tests / methods
  • Male
  • Predictive Value of Tests
  • Sex Factors

Substances

  • Cystatin C
  • Creatinine