Evaluation of Renal Function By Cystatin C in Renal Transplant Recipients

Objectives: We evaluated cystatin C concentration as a marker of glomerular filtration rate in renal transplant recipients, and its correlation with creatinine-based glomerular filtration rate by urinary creatinine clearance, and the Cockroft-Gault and Modification of Diet in Renal Disease formulas. Materials and Methods: In this cross-sectional study, we measured serum cystatin C levels and its correlation with serum creatinine, creatinine clearance, and glomerular filtration rate using the Cockroft-Gault formula and Modification of Diet in Renal Disease formulas. Results: One hundred two recipients between June and December 2012, were examined. The mean subject age was 31.87 +/- 8.37 years; the male:female ratio was 4.3:1. Mean serum creatinine concentration was 141.44 +/- 43.31 mu mol/L (1.60 +/- 0.49 mg/dL) and serum cystatin C 122.09 +/- 38.95 nmol/L (1.63 +/- 0.52 mg/L). Serum cystatin C was significantly correlated with serum creatinine (r=0.90; P < .001), creatinine clearance (r=0.77; P <. 001), and the Cockroft-Gault (r=0.73; P <. 001) and the Modification of Diet in Renal Disease formulas (r=0.82; P < .001). We assessed the correlation among serum cystatin C with serum creatinine, creatinine clearance, the Cockroft-Gault and Modification of Diet in Renal Disease at 1, 2-3, 4-5, and more than 5 years after transplant. The correlation between serum cystatin C and serum creatinine ranged from 0.8 to 1.0; cystatin C and creatinine clearance ranged from 0.8 to 0.85; serum cystatin C and the Cockroft-Gault formula ranged from 0.7 to 0.8; and serum cystatin C and the Modification of Diet in Renal Disease formulas ranged from 0.8 to 0.84. Conclusions: Our results show that serum cystatin C is a reliable marker for estimating glomerular filtration rate among renal transplant recipients. This test can determine the glomerular filtration rate of renal transplant recipients on follow-up. Further studies are required to establish serum cystatin C as a standard test for monitoring glomerular filtration rate in transplanted patients.