ENZYMATIC ERYTHROCYTE CREATINE DETERMINATIONS AS AN INDEX FOR CELL AGE

Creatine concentration in red blood cells was determinated after ammoniumsul-fate precipitation on a clear hemoglobin-free filtrate with a new enzymatic assay making use of bacterial creatinase. The method described is more specific than Griffiths' method and can easily be mechanised and adapted for use in a routine laboratory using classical automated equipment. By contrast with Griffiths' method no significant interferences of amino acids and creatine-like molecules were found. Reference values for this method were 0.379 ± 0.076 mmol/l. In patients with high turnover of erythrocytes, e.g. haemodialysis patients (0.529 ± 0.122 mmol/l), and renal insufficiency patients (0.565 ± 0.145 mmol/l), significantly increased creatine concentration in erythrocytes were observed. Low erythrocyte creatine concentrations were found in chronic ambulatory dialysis patients (0.311 ± 0.042 mmol/l). © 1990.