Sir.—Obstructive uropathy can be complicated by a defect in urinary concentrating ability that results in marked losses of water and electrolytes after relief of the obstruction. We describe a neonate with posterior
urethral valves who had a marked postobstructive diuresis. Hydrochlorothiazide and indomethacin were used to prevent dehydration. The defect in urine concentration and polyuria recurred on discontinuation of indomethacin and hydrochlorothiazide therapy, but improved after therapy with both drugs was restarted.
Patient Report.—A 6-day-old neonate was admitted for evaluation of abdominal distention, decreased urine output, swelling of the penis and scrotum, and poor feeding, which began 1 day before admission to the hospital. He was born at 37 weeks' gestation by normal spontaneous vaginal delivery after normal pregnancy and labor. He was discharged from the hospital at age 2 days. Results of physical examination showed marked distention and tenderness of the abdomen, with swelling of the penis