Life-Threatening Hyponatremia, Hyperkalemia, and Shock in Infancy: Not Always Congenital Adrenal Hyperplasia

Hyponatremia and hyperkalemia, though uncommon in infancy, are potentially life-threatening electrolyte disturbances. We discuss a case of secondary pseudohypoaldosteronism (PHA) in a six-month-old male presenting with recurrent vomiting, severe hyponatremia (119 mmol/L), hyperkalemia (6.6 mmol/L), and metabolic acidosis (bicarbonate: 9 mmol/L). The patient's condition rapidly deteriorated with hypotension and respiratory distress requiring intensive care and mechanical ventilation. Investigations identified an Escherichia coli urinary tract infection (UTI), and further laboratory tests revealed markedly elevated serum renin and aldosterone levels, consistent with secondary PHA associated with UTI in infancy. This report explores the incidence, proposed pathophysiology, and management strategies for secondary PHA. Additionally, we provide information to aid in differentiating among the potential causes of similar biochemical abnormalities, including congenital adrenal hyperplasia (CAH), in pediatric patients.