Objective: Serum cystatin C measurement is routinely used for glomerular filtration rate (GFR) assessment in last years – comparison of diagnostic efficacy for serum cystatin C and ß-2-microglobulin for declension of GFR estimation. Material and Methods: 71 patients, in all of them GFR was estimated from creatinine clearence [1], by Cockcroft and Gault calculation [2] and from cystatin C values [3]. Creatinine was measured in serum and urine with enzymatic method, serum cystatin C and ß-2-microglobulin with immunoturbidimetry. Sera 1/Cystatin C a 1/creatinin indexes were performed. Results: Serum cystatin C and ß-2-microglobulin values correlated with creatinine concentrations (r = 0.89, r = 0.93; P < 0.01). There were positive correlations between 1/cystatin C and creatinine clearence (r = 0.81; P < 0.01), between 1/cystatin C and GFR by Cockcroft and Gault (r = 0.81; P < 0.01) and between 1/creatinine and GFR from cystatin C (r = 0.85; P < 0.01). Comparable diagnostic efficacy among cystatin C and ß-2-microglobulin measurement with regard to the declension of creatinine clearance was detected; sensitivity 94.4%, or 91.7%, specificity 88.2 %, or 94.1% for the cystatin C cut-off values 1.05 mg/l and for the ß-2-microglobulin cut-off values 2.9 mg/l. Conclusion: Cystatin C has good diagnostic efficacy for the reduction of GFR estimation. In individuals without neoplastic disorders, inflammation or catabolism, ß-2-microglobulin has comparable diagnostic efficacy, too.

        Key words: cystatin C, ß-2-microglobulin, creatinine, GFR, renal disorders.