Purpose: To assess application of cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) as biomarkers for renal ischemic injury. We also evaluated the use of allopurinol as a renoprotective agent. A second goal was to assess cystatin C as a biomarker in patients undergoing partial nephrectomy. Methods: Using 58 Sprague-Dawley rats, we evaluated urinary cystatin C (n=26) and NGAL (n=32) as a biomarker for renal ischemia injury. Half of the rats were pretreated with allopurinol; the other cohort served as a control. The right renal hilum was ligated in all rats, thereby creating a solitary kidney model. After a 30-minute stabilization period, the left hilum was clamped for time periods of 15, 30, and 60 minutes. Urinary levels of cystatin C and NGAL were then measured at the following time points: Preclamp (after the 30-minute stabilization period) and postclamp (30, 45, and 60 minute periods after unclamping). For our clinical subjects, serum cystatin C levels (n=17) were obtained preoperatively, at the induction of anesthesia before robot-assisted partial nephrectomy, immediately postoperatively, and on postoperative days 1 and 2. Three of these patients had their tumors excised off clamp and served as controls. We then estimated glomerular filtration rate by using the Creatinine-Cystatin C Equation. Results: Urinary levels of cystatin C and NGAL increased after renal clamping. The 30-minute period of ischemia demonstrated the greatest increase of these biomarkers. Allopurinol did appear to serve a renoprotective function in those animals undergoing 30-minute clamp times. In our clinical patients, the serum cystatin C levels did increase at each postoperative time point, but remained nonelevated in the control group. Conclusions: Cystatin C and NGAL both appear to be useful biomarkers of renal injury. Studies with larger numbers are needed, however. Also, allopurinol does exhibit renoprotective effects against ischemic injury.
ASJC Scopus subject areas