Abstract
Background: Early detection of patients with chronic kidney disease is of great importance. This study developed reference limits for serum creatinine and serum cystatin C concentrations and for the estimated glomerular filtration rate (eGFR) in healthy subjects from the general population aged 25–65 years.
Methods: This study defined a reference population including 985 subjects from the first follow-up of the Study of Health in Pomerania. Serum creatinine was measured with a modified kinetic Jaffé method. Serum cystatin C was measured with a nephelometric assay. The eGFR was calculated from serum creatinine according to the Cockcroft-Gault (eGFRCG) and the Modification of Diet in Renal Disease (eGFRMDRD) equation, respectively, as well as from serum cystatin C according to the formula by Larsson (eGFRLarsson). Non-parametric quantile regression was used to estimate the reference limits. For serum creatinine and serum cystatin C the 95th percentile and for eGFRCG, eGFRMDRD and eGFRLarsson the 5th percentile were selected as reference limits. All data was weighted to reflect the age- and sex-structure of the German population in 2008.
Results: The reference limits for serum creatinine (men: 1.11–1.23 mg/dL; women: 0.93–1.00 mg/dL) and serum cystatin C levels (men: 0.92–1.04 mg/L; women: 0.84–1.02 mg/L) increased with advancing age. The reference limits for eGFR decreased with increasing age (eGFRCG men: 106.0–64.7 mL/min, women 84.4–57.9 mL/min; eGFRMDRD men: 82.5–62.2 mL/min/1.73 m2, women 75.0–58.2 mL/min/1.73 m2; eGFRLarsson men: 85.5–72.9 mL/min, women 94.5–75.7 mL/min).
Conclusions: This study presents age- and sex-specific reference limits for five measures of renal function based on quantile regression models.
©2012 by Walter de Gruyter Berlin Boston