The Efficacy of Serum Cystatin C & Creatinine Due to Diagnosis of Impaired Renal Function in Cancerous Paitients Treated with Chemotherapeutic Agents such as Cisplatin

There is a considerable number of cancerous patients undergoing the treatment of chemotherapy with Cisplatin and it is of undeniable importance to truly estimate their renal function. Besides, there are several reports owing to the more effectiveness of serum level of Cystatin C (Cys C) than creatinine (Cr) in diagnosis of early stages of impaired renal function. Therefore, this study was carried out to compare the diagnostic power of Cys C with Cr in predicting the reduced renal function, on patients referred to Imam Hossein Hospital between 2006-2008.

This diagnostic clinical trial was conducted on cancerous patients whom undergone the chemotherapy courses with Cisplatin. Serum creatinine (with RI 1000 combasmira) and serum Cystatin C (with turbidimetery (PETIA)) were measured, before and after the chemotherapy courses. Renal function tests were performed along with creatinine clearance of 24hr urine. Positive and negative predictive values (PPV, NPV) and the accuracy of both serum Cr and Cys C were analyzed by Chi-square test.

We studied 80 subjects (mean age 52±11 years old, 32 men and 48 women). Out of them, 40 patients had experienced reduced renal function. Positive predictive value and negative predictive value of Cystatin C were 88.3% and 94.6%, respectively. On the other hand, PPV and NPV of serum creatinine were 85.7% and 69.2%, respectively. There were 7 samples (8.7%) of false positive and negative results through the serum Cys C method, although in serum Cr, there were 20 samples (25%) with false positive and negative results (P< 0.01). Moreover, the serum levels of Cr and Cys C did not change after chemotherapy.

This study revealed that in contrast to creatinine, serum Cystatin C can preliminarily diagnose the early stages of impaired renal function.