Pseudohypoaldosteronism: Fulminant Presentation in a Premature Infant

• Shortly after birth, a 1,860-g premature male newborn with respiratory distress syndrome had brisk diuresis, rapid weight loss, and severe hyponatremia despite aggressive Na and fluid replacement. The serum cortisol level was normal, and the 17-OH progesterone concentration was low. He did not show any response to treatment with dexamethasone and desoxycorticosterone acetate. Results of renal function studies were within the normal range for his gestational age. The serum aldosterone level and plasma renin activity were grossly elevated, confirming the diagnosis of pseudohypoaldosteronism. This uniquely early and dramatic presentation was attributed to immaturity of the proximal renal tubule at 32 weeks' gestation. The subsequent improvement paralleled the rapid maturation of the kidney after birth. ( Am J Dis Child 1983;137:738-740)