Bartter Syndrome Presenting as Arginine-Vasopressin Resistance: A Report of 2 Cases.

BACKGROUND Bartter syndrome is a rare, inherited salt-wasting tubulopathy caused by mutations in 1 of 6 genes that express ion transport channels in the thick ascending limb of nephrons. Excessive prostaglandin E2 and associated hyperreninemic hyperaldosteronism occurs, causing polyhydramnios, polyuria, prematurity, failure to thrive, and characteristic physical features. Hypokalemia, hypochloremic metabolic alkalosis, and, depending on the affected gene, hypercalciuria and nephrocalcinosis are hallmarks of Bartter syndrome. CASE REPORT A 9-month-old male infant, born prematurely due to polyhydramnios, presented in the Emergency Department with dehydration due to incoercible vomiting and significant polyuria. A 6-year-old male infant with a previous history of prematurity due to polyhydramnios was referred to the Pediatric Endocrinology Department due to short stature and notable polydipsia and polyuria. Considering these marked symptoms, both cases triggered suspicion and started workup for arginine-vasopressin insufficiency/resistance. However, during the investigations, a broader clinical revision revealed that both had dysmorphic physical features (triangularly shaped face, prominent forehead, protruding ears, drooping mouth), poor growth, impaired weight gain, and typical biochemical findings (hypokalemic metabolic alkalosis, hypercalciuria, secondary hyperaldosteronism) of Bartter syndrome. Genetic testing confirmed the diagnosis of Bartter syndrome types 1 and type 2, respectively, and this diagnosis allowed proper treatment and significant clinical improvements, personalized follow-up, and genetic counseling for parents desiring further healthy pregnancies. CONCLUSIONS Here, we present clinical and follow-up findings of 2 patients with Bartter syndrome types 1 and 2 discovered upon a broader clinical revision of suspected arginine-vasopressin insufficiency/resistance. We also review pertinent data on diagnosis and management of this challenging syndrome.