VALIDATION OF RENAL OUTPUT EFFICIENCY AS AN OBJECTIVE QUANTITATIVE PARAMETER IN THE EVALUATION OF UPPER URINARY-TRACT OBSTRUCTION

This is a preliminary study of the parameter, renal output efficiency (ROE), for the quantitation of furosemide (frusemide) response in diur esis renography. This is calculated by a technique independent of vari ations in uptake rate by the kidneys. Eleven healthy volunteers and 34 patients suspected of upper urinary obstruction were, subjected to ga mma camera studies using Tc-99m-MAG, and a standard protocol. Furosemi de was given at 18 min after the study was started. The ROE was calcul ated in each kidney and the results were correlated with final diagnos is. The range of ROE in healthy individuals varied between 82% and 98% (mean = 91.6%); while obstructed kidneys showed significantly reduced values (p < 0.001) ranging between 30% and 76% (mean = 56%). In the d iagnosis of urinary obstruction, the ROE has a sensitivity of 91 %, sp ecificity of 94% and accuracy of 94%. ROE complements conventional diu resis renography and provides better diagnostic yield in patients with impaired renal function.