Pseudohypoaldosteronism type 1 and respiratory distress syndrome.

We present a patient born at 31 weeks gestation with respiratory distress syndrome (RDS) which did not respond to surfactant. He also developed hyponatremia, hyperkalemia and dehydration with increased sweat electrolytes despite high levels of serum aldosterone, thus systemic pseudohypoaldosteronism type 1 (PHA-1) diagnosis was made. Systemic PHA-1 is caused by mutations of amiloride-sensitive epithelial sodium channel (ENaC) genes. Because ENaC is a rate-limiting step for sodium absorption by epithelial cells, not only of the renal tubule but also of the lung epithelium, patients with PHA-1 with pulmonary symptoms have sometimes been reported. However, our patient appears to be the second reported human case of both neonatal RDS and PHA-1, and the first description, with increased sweat electrolytes, of a premature baby with systemic PHA-1 and RDS.