The authors review the diagnostic potential of cystatin C. Diagnostic effectivity of serum cystatin C for the assessment of the glomerular filtration rate is better or at least comparable with serum creatinine or creatinine clearance. These facts are proved by ROC analysis. Diagnostic sensitivities and specificities depend on selected cut-off points and analytical methods. Both sensitivity and specificity are frequently described as better for cystatin C than for creatinine. Biological intraindividual variability of serum cystatin C seems to be higher in comparison to creatinine. However, this can be the result of sensitive reflection of slight changes in the glomerular filtration rate. The last part of the review describes different diagnostic areas where cystatin C can serve as an indicator of pathological renal function.

        Key words: cystatin C, glomerular filtration rate, creatinine, diagnostic sensitivity, diagnostic specificity, ROC analysis, biological variability.