Serum Concentration of Cystatin C, Factor D and β2‐Microglobulin as a Measure of Glomerular Filtration Rate

ABSTRACT. Serum concentrations of creatinine and of the three low molecular weight (LMW) proteins cystatin C, factor D of the complement system and β2‐microglobulin were measured in 135 consecutive patients, whose glomerular filtration rates (GFR) were determined by Cr‐EDTA. In the total patient series, the reciprocals of S‐creatinine and S‐cystatin C were numerically and, in males, significantly more closely correlated to GFR than the reciprocals of S‐factor D. The reciprocals of β2‐microglobulin showed a weaker correlation to GFR than those of the other three substances. The calculated glomerular elimination rates of creatinine, cystatin C and factor D were normally distributed, in contrast to those of β2‐microglobulin. According to data presented so far, cystatin C seems to be the LMW protein of first choice when GFR is to be estimated by measuring the plasma concentration of a LMW protein. 1985 Association for the Publication of the Journal of Internal Medicine (Less)