Gender does not influence cystatin C concentrations in healthy volunteers

BACKGROUND: Current data are conflicting about the influence of gender on cystatin C concentrations. The goal of this study was to determine the reference interval for serum cystatin C in normal Brazilian subjects, taking into account the influence of gender. METHODS: Ninety-seven healthy volunteers, aged 18-70 years, 44% male, had glomerular filtration rate (GFR) measured using a (51)Cr-EDTA method and estimated with the Modification of Diet in Renal Disease (MDRD) study equation. Serum cystatin C was measured using a turbidimetric method, and creatinine by the Jaffe method. RESULTS: Mean serum cystatin C was not significantly different between males and females, 0.62 +/- 0.12 vs. 0.65 +/- 0.12 mg/L, respectively (p = 0.26). However, median serum creatinine was significantly higher in men [97 (80-115) vs. 80 (53-88) micromol/L; p = 0.0001]. There were also no significant differences between genders with respect to GFR measured using (51)Cr-EDTA (103 +/- 14 for males and 106 +/- 19 mL/min/1.73 m(2) for females, p = 0.47), and estimated with the MDRD equation (86 +/- 12 vs. 83 +/- 16 mL/min/1.73 m(2), respectively, p = 0.24). CONCLUSIONS: There was no effect of gender on serum cystatin C, as well as on measured and estimated GFR.