Transient Primary Renal Tubular Acidosis During Pregnancy: A Case Report.

Distal renal tubular acidosis (dRTA) can result from mutations in the SLC4A1 gene, which encodes the anion exchanger 1, a protein essential for bicarbonate-chloride exchange in the distal nephron. Anion exchanger 1 dysfunction disrupts acid-base homeostasis, leading to the development of non-anion gap metabolic acidosis. Transient, pregnancy-related presentations of dRTA are rare and remain poorly characterized. We report the case of a 35-year-old woman who, at 25 weeks of gestation, was found to have severe hypokalemia, normal anion gap metabolic acidosis, and a positive urinary anion gap, consistent with dRTA. After the delivery of a healthy, full-term newborn, her electrolyte abnormalities resolved spontaneously. Genetic testing revealed a pathogenic SLC4A1 mutation, confirming autosomal dominant dRTA. This case highlights a rare, transient form of genetically confirmed dRTA unmasked during pregnancy. It emphasizes the importance of evaluating persistent hypokalemia during pregnancy and considering genetic testing, even in asymptomatic individuals. Early recognition can guide appropriate management and genetic counseling for both patients and their offspring.