Treatment of congenital nephrogenic diabetes insipidus by hydrochlorothiazide and cyclooxygenase-2 inhibitor

A 1-month-old male infant presented with failure to thrive, polyuria, and severe hypernatremic dehydration. Based on family history, lack of response to vasopressin, and normal sonography of the urinary system, the diagnosis of congenital nephrogenic diabetes insipidus (cNDI) was established. The infant responded well to indomethacin in combination with hydrochlorothiazide (HCTZ), but quickly developed gastrointestinal bleeding. The substitution of indomethacin by amiloride and later by tolmetin was found to be ineffective. Treatment with HCTZ (3 mg/kg per day) and rofecoxib (1 mg/kg per day, both divided into three doses) combined with a low-salt formula resulted in a dramatic decrease in urinary free water losses. No side effects of the combination were noted. At age 8.5 months, the infant demonstrated catch-up growth and normal neurodevelopmental milestones. We conclude that the combination HCTZ/cyclooxygenase-2 inhibitor could be successfully used to treat infantile cNDI.