Creatinine and cystatin C-based evaluation of renal function among obese subjects in Benin City, Nigeria.

Obesity is a recognized worldwide epidemic with increasing prevalence in developing nations. Studies have shown that obesity is an independent risk factor for the development of chronic kidney disease (CKD) besides its link with diabetes mellitus and hypertension. We evaluated the renal status of obese patients using both the established [creatinine (Cr)] and new (cystatin C) markers of renal function. This was a cross-sectional study. Fifty-nine consenting adults attending the clinic for routine medical checks were recruited for this study. They were divided into obese and non-obese based on their body mass index. Serum from specimens collected were assayed for Cr and cystatin C. CKD equations were used to estimate glomerular filtration rate based on Cr (eGFR-Cr), cystatin C (GFR-Cystatin), and Cr/cystatin C (GFRCr/cystatin) while modification of diet in renal disease equation was also used to eGFR-Cr. The eGFR results generated were compared in assessing renal function. The obese participants and the controls were age-matched (50.6 ± 9.7 vs. 50.7 ± 7.8 years, P = 0.2). The obese participants had a significantly higher serum cystatin C (1.3 ± 0.7 vs. 0.9 ± 0.4 mg/L, P < 0.001) and significantly lower eGFR-cystatin C (75.4 ± 38.9 mL/min/1.73 m vs. 90.9 ± 25.1 mL/min/1.73 m, P < 0.001) than the controls, respectively. There was a significant difference between the eGFR-Cr and eGFR-cystatin C in the obese participants (97.4 ± 21.4 vs. 75.4 ± 38.9 mL/min/1.73 m), P = 0.019). The results showed that mild renal impairment exists among obese participants. Routine assessment is recommended to pre-empt deterioration in renal function. Cystatin C appears to be a better marker of renal function in obesity than serum Cr.