Diagnostic potential of diuresis renography: limitations by the severity of hydronephrosis and by impairment of renal function.

Eighty ureterorenal units (65 patients) with upper urinary tract dilatation underwent pressure perfusion studies and diuresis renographies separated by short intervals. Pressure perfusion studies were evaluated as suggested by Whitaker, while wash-out curves of diuretic renographies were analysed quantitatively by calculating peak elimination rates. Upper urinary tract volume was estimated from i.v. urographies and measured directly in 21 cases. Renal function was assessed from base-line renograms and plasma creatinine levels. In patients with minor upper urinary tract dilatation (less than 30 ml) the two procedures agreed in 88% of cases, in those with massive dilatation (greater than 70 ml) agreement was limited to 58%. Diuretic renal scans were more often obstructed than pressure perfusion studies in the latter situation. The effect of severely reduced renal function was less prominent than that of massive dilatation. This was confirmed by the exaggerated response to frusemide reflected by urinary flow measurements in patients with a creatinine clearance of 10 ml min-1 or less. Of the eight patients with severely reduced renal function, who did not show full agreement between the procedures, six had massive dilatation of the upper urinary tract.