Serum cystatin C versus creatinine in the assessment of allograft function in early periods of kidney transplantation

Introduction: Serum cystatin C is not routinely used in the evaluation of renal function and this may be due to its high cost, lack of adequate studies to approve the use of cystatin C and lack of accessibility and reliability. Many kidney transplanted patients encounter with decreased performance before creatinine rising and go toward rejection without certain actions. Certainly, the early detection of renal function reduction can prevent spiritual and physical damage among patients. Objectives: This study was aimed to determine the predictive value of serum cystatin C and creatinine in the assessment of allograft function in the early period after kidney transplantation in Urmia city, Iran. Patients and Methods: In this prospective study, serum creatinine, cystatin C and glomerular filtration rate (GFR) of 49 kidney transplanted patients in the 3rd, 8th and 14th day were measured and compared together. The correlation of creatinine and cystatin C was examined using Spearman’s correlation. ROC curves were used to investigate sensitivity and specificity. Results: In this study, there was a statistically significant relationship between serum levels of creatinine and serum levels of cystatin C in 3rd, 8th and 14th day. The sensitivity and specificity of cystatin C in 14th day were 76% and 91.2%, respectively and for creatinine were 72% and 75% respectively, indicating cystatin C is a more sensitive indicator compared to creatinine on the 14th day in the presence of loss of GFR below 60 mL/cc. Conclusion: Serum cystatin C as a valuable marker can be an effective predictor marker of renal function reduction beside creatinine. Due to high cost of measuring kits of serum cystatin C, it is not possible to use this marker in all transplanted patients in the world. Therefore, we can use this marker in high-risk patients with probability of transplantation rejection.