Split renal function tests by method of Howard were performed in patients with renovascular hypertension and in patients with essential hypertension or chronic nephritis as control.
Statistical analysis showed that the functional disparities of the two kidneys in the control group were within 30% decrease in all parameters such as urine flow, urine sodium concentration, urine creatinine concentration, creatinine clearance and excretion fraction of filtered sodium (EFNa).
In patients with unilateral main renal artery obstruction in whom surgical procedure alleviated the hypertension, the results of the preoperative test showed the urine flow and the EFNa of th affected kidney decreased more than 30% of the normal mate kidney without exception and the other parameters in a few cases were distributed within the range of the control group.
It is concluded that reduction of the urine flow and the EFNa of the affected kidney by more than 30% of the other kidney is a characteristic pattern for the unilateral main renal artery obstruction with hypertension.
Additional animal experiments showed that the pattern of the split renal function in dogs with unilateral main renal artery obstruction was not the same with that of clinical cases in an acute stage, and that osmotic diuresis for split renal function test resulted in a decrease of the difference between the two kidneys except the urine flow.
