Assessment of renal function and acute rejection using Cystatin C and kidney injury Molecule-1 in renal transplant recipients

Purpose: Kidney injury molecule (KIM)-1, a transmembrane-tubular protein, is excreted in the urine within 12 h of the initial ischemic insult and before regeneration of the epithelium. Cystatin C (CysC) a low-molecular-weight nonglycosylated protein has been shown to be a good marker of kidney function. We aimed to evaluate the levels of KIM-1 and CysC immediately after transplantation as an early marker. Subjects and Methods: Urine and blood samples were collected from prospective renal transplant patients with chronic allograft dysfunction (CAD) at baseline and during the follow-up period at the interval of 12, 24 h, 7 th postoperative day 15 th and 6 m, and compared with healthy controls (HC) for KIM-1 CysC S.creatinine (SCr) and creatinine clearance. Results: Kidney transplant recipients showed significantly higher KIM-1and CysC values than the control group. Nonparametric receiver-operating characteristic (ROC) curve of the renal function with an area under the curve of 0.518 KIM-1, CysC was 0.841 and creatinine 0.74 indicating CysC at 12 h posttransplant (post-Tx) is a better biomarker among three. ROC of acute rejection (AR) of KIM-1 at 24 h post-Tx showed sensitivity of 0.938. ROC for distinguishing between graft survival and failure at 1 year showed a sensitivity of 0.763 for CysC, In CAD, both KIM-1and CysC were increased as compared to HC. Conclusion: Both KIM-1 and CysC are useful markers for predicting AR, renal function. Elevated urinary levels of KIM-1 independently predict AR. CysC is a valuable marker of predicting the long-term outcome.