[Effective renal plasma flow with I-131-hipuran: evaluation of a method with four extractions]

The aim of this work was to evaluate a method for the estimation of the effective renal plasma flow (ERPF) using sodium 131I-o-hippurate (OIH) by means the bicompartmental analysis of the radioactive concentration of 4 plasma samples, analyzing the error obtained respecting to the multi-sample method and comparing it with those obtained with other simplified methods. We calculated the ERPF from 62 patients using the multi-sample method as standard, the method based in a single sample at 44 minutes p.i., a method based in 2 samples from the first exponential, 4 methods based in 2 samples from the second exponential, one method based in 3 samples and 5 methods based in 4 samples (2 from the first exponential and 2 from the second exponential). Each simplified method was compared to the standard method and their absolute error (AE) and standard estimation error (SEE) were calculated. The method based in the 4 samples withdrawn at 4, 10, 30 and 60 minutes p.i. was the best of them with a correlation factor with the standard equal to 0.997, an EA that ranged from -63 ml/min to 49 ml/min (mean: -4 ml/min) and a SEE of 19.5 ml/min.