Renal tubular acidosis (RTA) is a renal cause of non-anion-gap metabolic acidosis characterized by low urinary ammonia excretion. This condition has a low prevalence, and various congenital and acquired etiologies. To date, only a few cases of idiopathic RTA uncovered during pregnancy have been reported.

A previously healthy 32-year-old Korean woman at 30 wk of gestation was admitted to Pusan National University Hospital with preterm labor. At admission, the patient presented with hypokalemia, non-anion-gap metabolic acidosis, and nephrocalcinosis. Distal RTA was diagnosed based on laboratory blood and urine findings and imaging examinations. Various tests, including next-generation gene sequencing panels for nephropathy, were performed to determine the etiology of the disease, which indicated that it was idiopathic. The patient received sodium bicarbonate and potassium chloride supplementation. After 3 wk, she delivered a baby who was subsequently diagnosed with corpus callosum agenesis and colpocephaly. During regular follow-ups for 6 mo postpartum, her hypokalemia and metabolic acidosis were gradually resolved, and medications eventually discontinued.

Herein we describe a case of idiopathic distal RTA discovered during pregnancy. Hypokalemia and metabolic acidosis resolved spontaneously after delivery.