Long-Standing Hypokalemia and Hypomagnesemia in a 61 Year-Old Woman: A Delayed Diagnosis of Gitelman Syndrome.

BACKGROUND: Gitelman syndrome (GS) is an autosomal recessive renal tubular disorder characterized by a distinct biochemical profile, including hypokalemia, metabolic alkalosis, hypomagnesemia, and hypocalciuria. Due to its often mild or nonspecific clinical presentation, GS is frequently misdiagnosed as idiopathic hypokalemia, leading to prolonged symptomatic treatment without a definitive etiologic diagnosis.

CASE PRESENTATION: We report the case of a 61-year-old female with a one-year history of unexplained, refractory hypokalemia and hypomagnesemia. The diagnosis had been delayed as clinical efforts were primarily focused on escalating electrolyte supplementation. Systematic evaluation of renal electrolyte handling revealed inappropriate urinary potassium and magnesium wasting in conjunction with marked hypocalciuria. In addition, a symptom-oriented family history, documenting chronic fatigue and muscle cramps in her sibling, served as a critical diagnostic clue. Genetic testing confirmed the diagnosis by identifying compound heterozygous variants in the SLC12A3 gene. Following diagnosis, the patient was enrolled in the Korean National Medical Expense Support Program for rare diseases, ensuring structured long-term management.

CONCLUSIONS: This case underscores the importance of an etiologic approach over a purely treatment-focused one in patients with recurrent electrolyte imbalances. GS may be more prevalent than currently recognized, particularly among adults receiving empirical therapy for hypokalemia. Early clinical suspicion, grounded in urinary electrolyte indices and careful family history, is essential for timely diagnosis.