[Evaluation of the reliability of endogenous creatinine clearance as in indicator of renal function in ambulatory patients. I].

Clearance of the endogenous creatinine is a simple method for application, it is relatively cheap and applicable in almost all surroundings, but it is not reliable enough when the obtained results are concerned. This report shows the results of determining this clearance in comparison with radiosotope clearance 51 cr-EDTA, referent for clinical research, in 52 outpatients with primary and secondary kidney diseases. It was found that values of clearance of the endogene creatinine (Clkr) are significantly lower than the clearance 51 Cr-EDTA (ClEDTA) (t = 2.391, p < 0.01) and that the correlation between the two method is poor (r = 0.688). The source of mistakes should be looked for (and strictly controlled) when gathering diuresis, because the biochemical method of creatnine concentration determination of the biologic material itself is reliable enough.