Obstructive uropathy: frusemide test and analysis of renographic curve patterns

49 patients with clinically proven uropathy and 14 others suffering from nephropathy underwent quantitative 131I-OIHA renography, combined with a frusemide provocation test. In significant obstruction, diuresis reaction was typically less than 5% (predictive value of a positive test 76%). The renographic curves, derived from the renal cortex and from the pyelon were diverging, with the pelvic curve showing a continuous rise (predictive value of a positive test for the curve pattern analysis 92%). Non-obstructive dilatation of the urinary system was characterized by a high diuresis index (greater than 15%) (predictive value 82%). The curve pattern was plateau-like before and showed a converging course of cortical and pelvic activity spontaneously, at least after diuresis provocation (predictive value 75%). Nephropathy alone could exceptionally mimick both significant obstruction and non-obstructive dilatation. Qualitative renographic curve analysis combined with diuresis provocation renders a higher diagnostic yield regarding the dynamic state of questionable uropathy than either test alone.