Comparison Study of the Diagnostic Values of Serum Cystatin C and Creatinine in the Assessment of Renal Function in the Early Follow-up of Renal Transplant Patients

Early detection of decreasing glomerular filtration rate (GFR) is critical to prevent graft rejection in post-transplantation period. Serum creatinine has several drawbacks as a marker of GFR, so serum cystatin C has been proposed as an alternative GFR marker. Thus, we prospectively evaluated the diagnostic value of cystatin C measurements compared with serum creatinine in the early postoperative phase. Patients and In 78 renal recipients, serum creatinine and cystatin C were measured on the 3rd, 7th and 14th days of post-transplantation period. GFR was established by creatinine clearance with the cut-off point of 80 ml/min/1. 73 m2. The correlation between serum creatinine and cystatin C with GFR was determined. Sensitivity and specificity of these markers were analyzed by ROC procedures. There were 78 renal recipients (51 males and 27 females) with the mean age of 34. 56± 13. 36 years and mean body mass index (BMI) of 22. 36± 3. 46 kg/m2. Serum cystatin C was not influenced by gender, age and BMI. There was a significant correlation between serum creatinine and cystatin C levels with GFR on the 3rd, 7th, and 14th days (P< 0. 001). Analysis with ROC procedures showed a decrease in GFR (GFR< 80 ml/min/ 1. 73 m2) on the 7th day (P= 0. 023, AUC= 0. 694). Sensitivity and specificity of serum cystatin C were 67. 7% and 77. 9% respectively with the cut-off point of 2264 ng/ml. Cystatin C has good sensitivity to estimate the renal function in the early post-transplantation period, but its value as a marker of GFR is decreased at the end of the first week.