Serum cystatin C, a cysteine proteinase inhibitor, has been proposed as a marker of glomerular filtration rate (GFR). Serum cystatin C, serum creatinine and creatinine clearance were measured in 226 patients with various nephropathies, covering the entire range of renal function, to evaluate the efficacy of cystatin C as a screening test to detect reduced creatinine clearance in comparison to creatinine. Subgroups of 53 patients with glomerular and 26 patients with tubular impairment were compared to assess whether cystatin C performed differently in either glomerular or tubular impairment. Cystatin C detected reduced creatinine clearance with higher sensitivity (97 vs. 83%), and higher negative predictive value (96 vs. 87%) compared to creatinine. In parallel, 95% sensitivity of cystatin C as derived from receiver-operating characteristic plot was significantly higher (p < 0.05). In the subgroups with glomerular or tubular impairment, cystatin C and creatinine did not significantly differ with regard to efficacy. Serum cystatin C is as efficacious as serum creatinine to detect reduced GFR as measured by creatinine clearance. The efficacy of cystatin C as a screening test may even be superior compared to creatinine. In addition, the efficacy of cystatin C is independent of either glomerular or tubular impairment.

The performance of serum cystatin C as a screening marker of reduced creatinine clearance in renal transplantation was evaluated and compared to serum creatinine. In addition we studied whether cystatin C accurately reflects creatinine clearance over the entire range of transplant function. Serum cystatin C, serum creatinine, and creatinine clearance were measured in 110 adult renal transplant recipients. Cystatin C detected reduced creatinine clearance with the high sensitivity of 95 YO. Serum cystatin C and serum creatinine did not differ regarding 90 and 95 YO sensitivity, derived from the receiver-operating characteristics plot. We demonstrated a strong correlation and linear association between l/cystatin C and creatinine clearance over the entire range of transplant function,

The performance of serum cystatin C as a screening marker of reduced creatinine clearance in renal transplantation was evaluated and compared to serum creatinine. In addition we studied whether cystatin C accurately reflects creatinine clearance over the entire range of transplant function. Serum cystatin C, serum creatinine, and creatinine clearance were measured in 110 adult renal transplant recipients. Cystatin C detected reduced creatinine clearance with the high sensitivity of 95 YO. Serum cystatin C and serum creatinine did not differ regarding 90 and 95 YO sensitivity, derived from the receiver-operating characteristics plot. We demonstrated a strong correlation and linear association between l/cystatin C and creatinine clearance over the entire range of transplant function,