Renal distension in response to water-soluble contrast medium and various diuretics

Measurement of the increase in area of the renal silhouette, as it appears on radiographs following the administration of water-soluble contrast medium and certain diuretics, seems to be useful in the diagnosis of renovascular hypertension. In order to assess the optimal technique for such measurements, washout urography was performed in 32 hypertensive patients in two consecutive examinations so that the distensive effect of etacrynic acid, furosemide and hypertonic mannitol, respectively, were compared with that of urea in the same patients. In spite of their stronger diuretic effect, none of the above-mentioned diuretics caused a greater renal distension than urea, the maximum increase in area of the renal silhouette being about 7 to 20%, average about 11%. Since urea is probably the best siuted diuretic for the washout test, it seems to be the drug of choice for these diagnostic procedures.