Cystatin-C and Urinary Albumin-to-Creatinine Ratio as Complementary Markers of Renal Involvement in Adults with Metabolic Syndrome: A Hospital-Based Comparative Study

Background: Metabolic syndrome (MetS) is associated with an increased risk of renal dysfunction, but conventional measures of kidney function may not fully characterize early renal involvement. Cystatin-C provides an alternative marker of glomerular filtration, while urinary albumin and the urinary albumin-to-creatinine ratio (UACR) provide information on glomerular permeability and albumin leakage. Evaluation of these complementary markers may provide a broader assessment of renal involvement in individuals with MetS. Material and Methods: We conducted an analytical cross-sectional comparative study among 360 adults, including 180 participants with MetS and 180 age- and sex-matched controls. We defined MetS according to the International Diabetes Federation 2006 criteria. We assessed serum cystatin-C, urinary albumin, and UACR alongside clinical and anthropometric parameters. We evaluated associations between waist circumference (WC), waist-to-hip ratio (WHR), and renal parameters using correlation analysis. We considered statistical significance at p<0.05. Results: Serum cystatin-C was significantly higher among participants with MetS than controls (1.08 ± 0.22 vs 0.92 ± 0.16 mg/L; t=8.29, p<0.001). Urinary albumin was also significantly higher in the MetS group (24.53 ± 16.86 vs 13.04 ± 8.38 mg/L; t = 8.19, p < 0.001). Similarly, UACR was significantly elevated among participants with MetS (38.45 ± 25.47 vs 18.72 ± 10.58 mg/g; t=9.60, p<0.001). Most correlations between anthropometric indices and renal parameters were not statistically significant. We observed a weak inverse correlation between WHR and cystatin-C (r=-0.193, p=0.009). Urinary albumin and UACR did not differ significantly across the 2-, 3-, and 4-component MetS subgroups. Conclusion: Adults with metabolic syndrome demonstrated significantly higher cystatin-C, urinary albumin and UACR than controls. These findings suggest that renal involvement associated with MetS may involve both altered filtration and increased urinary albumin excretion. Cystatin-C and urinary albumin assessment may therefore provide complementary information alongside conventional renal function testing. However, the cross-sectional design prevents inference of causality or chronicity.

Keywords: Metabolic syndrome; cystatin-C; albuminuria; urinary albumin; UACR; renal involvement; kidney function; glomerular filtration; chronic kidney disease.