Renal function in idiopathic hydronephrosis.

In 11 patients who underwent Anderson-Hynes pyeloplasty for unilateral hydronephrosis, renal function was examined with split-clearance technique immediately after the operation and 2-5 years postoperatively. The studies shortly after pyeloplasty showed decreased glomerular filtration rate (GFR) and renal plasma flow (RPF) in most of the hydronephrotic kidneys. GFR improved slightly during the follow-up period, but RPF did not increase. The tubular dysfunction, expressed as moderately increased fractional excretion of electrolytes, showed significant improvement only as regards magnesium. The study indicates that reconstructive surgery is not warranted if the aim is to improve renal function in an asymptomatic patient with normal total GFR. On the other hand, patients with pain caused by the renal obstruction should always be subjected to surgery.