Persistent tubular resistance to aldosterone in infants with congenital hydronephrosis corrected neonatally.

Renal function of 18 infants who had undergone surgery in the neonatal period because of severe congenital hydronephrosis was followed up for 5 to 36 months (mean +/- SD 21 +/- 10 months). In all cases the diagnosis was made prenatally by sonography and confirmed at birth by intravenous urography. Creatinine clearance developed normally in all the children. Eight had a reduction in maximal urinary concentrating ability after intranasal DDAVP; this defect was transient and resolved after 4 to 5 months in all but one child, in whom it persisted. However, other tubular abnormalities were present. Throughout the observation period, patient serum potassium concentrations were significantly higher than normal, paralleled by a significant increase in plasma aldosterone concentration but with normal excretion fraction of sodium and potassium. There were no disturbances of acid-base balance. These findings may be accounted for by a persistent partial reduced sensitivity of the distal tubule to the action of aldosterone despite normal renal function. This alteration is usually mild, but may constitute a persistent metabolic risk despite successful surgical intervention.