[Reliability and limitations of total and divided renal clearances as determined with a partially shielded whole-body counter (author's transl)].

Error and reproducibility of the total and divided renal clearance determination was investigated, using a partially shielded whole-body counter. The error of the total renal clearance determination using ortho-131I-hippuran (OIH) depends primarily on the downslope of the whole-body curve, i.e. on renal function. The error is as low as +/- 6% for clearance values of more than 100 ml/min and increases slowly with clearance values decreasing about 35 ml/min. The error of clearance values below 25 ml/min is higher than 50%. The error of the divided renal clearance using OIH is the same as the error of the total renal clearance. The reproducibility of the total OIH-clearance in single clearance periods was found to be +/- 6% and in repeated determinations +/- 12% (r = 0.97). The reproducibility of the divided renal OIH-clearance with scintillation probes showed an average deviation from the mean of +/- 10% (r = 0.87). The substitution of the scintillation probes by a scintillation camera and the use of regions of interest should diminish this error considerably. The results were compared with literature data on standard PAH- and inulin clearances.