URINARY LIVER TYPE-FATTY ACID BINDING PROTEIN AND PLASMA CYSTATIN C AS EARLY PREDICTORS OF CONTRAST INDUCED ACUTE KIDNEY INJURY

Abstract

Background: Contrast-induced acute kidney injury (CI-AKI) continues to have an increasing incidence, representing the third most common cause of hospital acquired acute kidney injury. It is a syndrome in which an acute renal dysfunction is diagnosed after the intravascular injection of contrast media. Acute renal injury is typically diagnosed by measuring serum creatinine that is an unreliable indicator during acute changes in kidney function; thus, the need for early sensitive biomarkers to detect acute kidney injury before the rise of creatinine has emerged. Urinary Liver type fatty acid binding protein is a newly emerging biomarker that might represent an early, sensitive and non-invasive biomarker for acute renal injury. Cystatin C is a cysteine protease inhibitor that demonstrated a high diagnostic value to detect AKI on the two days before creatinine elevation. Objective: The aim of our study was to elucidate if urinary L-FABP and plasma Cystatin C can be early predictors of AKI after contrast adminstration. Subject and methods: thirty three patients were included in this study, they were divided into two main groups; Group (I): 16 patients underwent coronary angiography for dioagnostic and therapeutic purposes, Group (II): 17 patients underwent computerized tomography using IV (high-osmolar) contrast media; then classified after the procedure to AKI group and Non AKI group according to the change in serum creatinine after 24 hours. Results: the basal value of both plasma cystatin c and urinary L-FABP is significantly higher in AKI vs non AKI groups indicating predictive value of both biomarkers before contrast exposure (AUC of urinary L-FABP = 0.837 (95%CI; 0.673 – 1.001); AUC of plasma Cystatin C = 0.742 (95%CI; 0.600 – 0.925)). After contrast exposure, both both plasma cystatin c and urinary L-FABP showed a highly statistically significiant elevation at 6 hours in the AKI group compared to the non AKI group, while there was no statistically significiant difference in serum creatinine (mg/dl) that showed significant elevation only after 24 hours; thus, both plasma cystatin c and urinary L-FABP may serve as early predictors of AKI after contrast adminstration before any significant change in serum creatinine (AUC of urinary L-FABP =1 (95%CI; 1 – 1); AUC of plasma Cystatin C =1 (95%CI; 1 – 1)). Conclusion: urinary L-FABP and plasma Cystatin C can be considered as predictive biomarkers of contrast induced nephropathy before contrast exposure and as early biomarkers after contrast exposure instead of serum creatinine, as their levels start to rise about 24 hours before any significant change in serum creatinine. Further studies are recommended using large number of patient. Keywords: L-FABP, cystatin c, contrast-induced nephropathy, high osmolar contrast.