The blood serum concentration of cystatin C (gamma-trace) as a measure of the glomerular filtration rate

The blood serum concentrations of creatinineand the low molecular weight proteins cystatin C, β2-microglobulin and retinol-binding proteinwere measured in 106 patients whose glomerular filtration rates were assessed by Cr-ethylenedi-aminetetraacetate (EDTA)-clearance determinations. The reciprocals of the serum concentrations of creatinine, cystatin Cand β2-microglobulin were closely correlated to the Cr-EDTA-clearance (r = 0.73, 0.75 and 0.70, respectively) in contrast to the corresponding values for retinol-binding protein(r = 0.39). The calculated values of the glomerular elimination rate for creatinineand cystatin Cwere normally distributed in contrast to those for β2-microglobulin. The calculated glomerular elimination rate of cystatin Cwas not correlated to age, sex, type of disorder or disease activity. The results demonstrate that the serum level of cystatin Cis a better measure of the glomerular filtration rate than the serum level of β2-microglobulin.