Serum cystatin C as a marker of renal function in patients with acute renal failure.

Serum creatinine level is the traditionally used tool to detect changes in renal function. Serum cystatin C (CC) has been suggested to be an equally effective marker of renal function. We measured the serum levels of creatinine and CC in 73 patients with acute renal failure (ARF) and 300 age and sex matched healthy controls. The serum CC was measured by particle enhanced nephlometric immunoassay (PENIA). As expected, the serum creatinine and CC levels were significantly higher in ARF patients than the healthy controls and serum CC levels correlated significantly with serum creatinine (r = 0.47, p< 0.0001). This correlation further increased for multiple measurements, (r = 0.51, p< 0.0001. No gender difference was noted. Serum CC also correlated significantly with calculated GFR. Correlation of serum CC with serum creatinine and calculated GFR was much greater in patients with deteriorating renal function, compared to patients with improving renal function (p< 0.0001). Our study further suggests that the serum CC is a good marker of renal function in ARF patients, especially those with worsening renal function. Further larger studies are needed to evaluate its role in detecting early ARF and institute possible intervention.