A Neonatal Salt-Wasting Crisis Mimicking Congenital Adrenal Hyperplasia: A Case of Transient Pseudohypoaldosteronism.

Salt-losing crisis in the neonate is a life-threatening event manifested by hyponatremia, hyperkalemia, and metabolic acidosis. Whilst this biochemical finding is classically seen in congenital adrenal hyperplasia (CAH), conditions of aldosterone action, such as pseudohypoaldosteronism (PHA), can also present with these findings but require different care. A four-week-old term male infant is described who was brought in with vomiting, lethargy, and anuria. At the time of admission, he was in shock with marked hyponatremia (119 mmol/L), life-threatening hyperkalemia (9.8 mmol/L), metabolic acidosis, and acute kidney injury (AKI). He needed resuscitation, treatment of hyperkalemia, and admission to pediatric intensive care. CAH was considered at the beginning, but newborn mass screening for 17-hydroxyprogesterone was normal, and serum cortisol before steroid therapy was adequate, so primary adrenal failure may be ruled out. Electrolytes and renal function returned promptly to normal after volume repletion, and the patient passed into a polyuric recovery. The clinical course, including rapid resolution of PHA, was consistent with transient (secondary) PHA related to severe volume depletion and prerenal AKI, resulting in temporary renal tubular resistance to aldosterone. This case illustrates the necessity to differentiate secondary PHA from CAH in neonates presenting with salt loss crises, since early recognition spares lifelong unnecessary steroid exposure and directs appropriate supportive care.