Serum cystatin C levels in renal transplant recipients.

Cystatin C is an emerging parameter for the assessment of renal allograft function. The objective of the study was to compare the efficacy of serum cystatin C (SCys) with the established parameter serum creatinine (SCr) in the assessment of renal function in renal transplant recipients (RTR). The glomerular filtration rate (GFR) of 30 renal transplant patients and 29 control subjects was determined using (99m)Tc Diethylene-triamine-penta-acetate (DTPA) method. SCr was measured using an automated Jaffe's assay and SCys was measured using latex particle enhanced turbidimetric immuno assay (PETIA). The modification of diet in renal disease (MDRD) formula was used to calculate GFR from SCr, while the Le Bricon formula was used to derive GFR based on SCys. Statistical analysis was performed using MedCalc software. SCr and SCys levels were significantly higher, while DTPA clearance was significantly lower in RTR (P < 0.0001) when compared with controls. The correlation coefficient (r value) between calculated GFR based on MDRD method and DTPA clearance was 0.343 (P = 0.06) while the calculated GFR based on Le Bricon formula was 0.694 (P < 0.001). The results have shown that SCys is a better parameter than SCr in assessing renal function in RTR. The inclusion of SCys as an additional parameter would certainly help in detection of even a marginal decline in renal function and also in adjusting the dosage of immunosuppressive drugs.