Diagnostic Challenges in Severe Electrolyte Imbalance in Early Infancy: A Case Report of Secondary Pseudohypoaldosteronism

Background: Secondary pseudohypoaldosteronism (PHA) is a rare, transient condition caused by renal tubular resistance to aldosterone, most commonly associated with urinary tract infection (UTI) and/or congenital anomalies of the kidney and urinary tract (CAKUT). It mimics primary adrenal disorders, presenting with life-threatening electrolyte disturbances in early infancy. Case Presentation: We report a male infant admitted twice within the first four months of life with severe dehydration, hyponatremia, hyperkalemia, metabolic acidosis, and acute kidney injury (AKI). Urine cultures grew Klebsiella pneumoniae and later Escherichia coli. Imaging studies demonstrated obstructive CAKUT, including posterior urethral valves, bilateral megaureters, hydronephrosis, and bladder diverticulosis. Congenital adrenal hyperplasia was excluded. Further evaluation showed markedly elevated plasma renin and aldosterone levels, confirming secondary PHA. The patient was successfully treated with intravenous fluids, electrolyte correction, and antibiotic therapy. Subsequently, oral sodium chloride and bicarbonate supplementation were added. Stepwise surgical correction of the urinary tract anomalies was initiated. Conclusions: Secondary PHA should be considered in infants presenting with failure to thrive, dehydration, hyponatremia, and hyperkalemia, particularly in the presence of UTI or CAKUT. Early recognition and differentiation from primary adrenal disorders are essential to prevent life-threatening complications. Prompt correction of electrolyte imbalance and management of the underlying urinary tract pathology are crucial for favorable outcomes.