Bartter Syndrome Type 2 in Adolescence: Clinical Features and Genetic Confirmation

Abstract Background Bartter Syndrome (BS) is a rare salt-losing tubulopathy characterized by impaired sodium reabsorption and excessive salt excretion. Type II Bartter Syndrome, usually presenting in the neonatal period, is associated with mutations in the KCNJ1 gene. Reporting this case adds to the limited data on late-onset presentations of BS type 2, highlighting its clinical variability. Case Presentation: An 18-year-old female presented with polydipsia, frequent urination, muscle cramps, and fatigue. She was found to have hypokalemic metabolic alkalosis, hypercalciuria, and hypomagnesemia. Imaging revealed bilateral renal medullary nephrocalcinosis. Genetic testing identified heterozygous mutations in the KCNJ1 gene, confirming BS type 2. The patient's birth weight was 2.7 kg, with no history of polyhydramnios or post-natal complications. Management included potassium and magnesium supplementation, and NSAIDs to inhibit prostaglandin synthesis. Conclusions This case underscores the importance of considering rare genetic renal tubular disorders like BS type 2 in patients with persistent electrolyte abnormalities, polyuria, and nephrocalcinosis. Genetic testing is crucial for diagnosis and management, which can significantly improve the patient's quality of life and prevent disease progression.