Chronic kidney disease (CKD) is a rapidly growing global health problem. Cystatin C has been proposed as an endogenous marker for the assessment of kidney function in CKD. The objective of the present study was to compare the serum cystatin C (Scys) and serum creatinine (Scr) in elderly patients with CKD. The glomerular flitration rate (GFR) of 92 patients was determined using 99m Tc- diethylene triamine penta-acetic acid (DTPA) clearance. Scr was determined by kinetic method using jaffe reaction. Scys was analysed by particle enhanced immuno turbidity (PETIA) method. Scys and Scr levels were significantly higher in the kidney failure group as compared with the advanced CKD group and advanced CKD group as compared with the moderate CKD (p <0.0001). When compared with DTPA clearance, the Pearson's correlation coefficient for Scys was -0.779 (p < 0.001) while for Scr, it was -0.609 (p< 0.001). The ROC plots had an 'area under the curve' value of 0.992 for Scys and 0.970 for Scr. The present study demonstrated that determination of Scys might be useful in the assessment of renal function in elderly patients with CKD and is a potentially better marker than Scr.

Keywords: cystatin C, creatinine, DTPA clearance, chronic kidney failure.