Renal function assessment of obese non diabetic and obese diabetic patients using serum Cystatin C

Abstract

Background: There is an annual 8% increase in the prevalence of chronic kidney disease (CKD). This is probably due to the lack of consistent surrogate markers of kidney function to identify early stages of the disease. AIM: This study is aimed at evaluating renal status of patients with obesity (with or without diabetes) using both Creatinine and Serum Cystatin C.

Materials and Methods: Seventy-six (76) consenting normotensive adults were recruited in a cross-sectional study carried out in a tertiary hospital. The study included 46 subjects (21 obese diabetic and 25 obese non-diabetic) and 30 non-obese euglycaemic controls. Analytical methods of kinetic Jaffe and immunoturbidimetry were used to assaycreatinine and cystatin C respectively. Estimated glomerular filtration rates (eGFR) was calculated for creatinine and cystatin C using CKD-EPI formula. Statistical analysis was done using SPSS Version 22. Level of significance was established at p<0.05.

Results: The obese subjects and the controls were age (52.2±9.4years vs 52.7±7.8years, p=0.32) and sex matched. The obese subjects had significantly higher serum Cystatin C than the controls (1.6 ± 1.0mg/L vs 0.9 ± 0.4mg/L, p<0.002). The subjects also had a significantly lower eGFR-Cr (87.8 ±23.4ml/min/1.73m² vs 90.9±+25ml/min/1.73m² p=0.035) and eGFRCystatin C (64.4±40.1ml/min/1.73m² vs 90.9±+25ml/min/1.73m² p= 0.005) than the controls. Thedifference was more significant in the obese diabetics. There was a significant difference between e GFR creatinine and e GFR cystatin C in the obese non diabetic subjects (98.2±18.9 ml/min, 80.8±36.8 ml/min) respectively p<0.05 and obese diabetics (75.3±22.4 ml/min, 44.9±35.4 ml/min) respectively p<0.05.

Conclusion: Cystatin C appears to be a more useful marker in assessment of renal function, and may be useful in early detection of decline in renal function.Mild renal impairment may exist in obesity and can be worsened by diabetes mellitus.

Key words: obesity, diabetes, Cystatin C