A newborn with type 1 Bartter syndrome: challenges in the treatment and development during 30 months follow-up-a case report.

Type I Bartter syndrome is a rare autosomal recessive tubulopathy resulting from mutations in the SLC12A1 gene, leading to defective sodium-chloride reabsorption in the thick ascending limb of the loop of Henle. Affected neonates typically present with profound fluid and electrolyte disturbances, polyuria, and metabolic derangements. Early diagnosis and individualized management are crucial to prevent life-threatening complications and support appropriate growth and development. We report the case of a male preterm infant born at 33 weeks' gestation following a pregnancy complicated by severe polyhydramnios requiring multiple amnioreductions. At 2 weeks of age, he was admitted with severe dehydration, acute kidney injury (creatinine 205 µmol/L; eGFR 8 mL/min/1.73m2), marked polyuria (300 mL/kg/day), and significant electrolyte abnormalities, including hyponatremia, hypokalemia, hypochloremia, and metabolic acidosis. During the first week of hospitalization, he developed necrotizing enterocolitis. Bartter syndrome was suspected based on the biochemical profile, perinatal history, and persistent electrolyte imbalance, and subsequently confirmed by identifying a pathogenic SLC12A1 variant (NM_001184832:c.1327G>A). Management required exceptionally high fluid volumes (280-310 mL/kg/day), intensive sodium and potassium supplementation, and gradual transition from parenteral to enteral nutrition. Following expert consultation, celecoxib was introduced (2.5 mg/kg twice daily), permitting stabilization of electrolyte homeostasis and discontinuation of parenteral nutrition by day 61 of life. Throughout hospitalization, complications included catheter-related inflammation, inferior vena cava thrombosis, anemia requiring transfusion, and stage II intraventricular hemorrhage. Serial renal ultrasonography demonstrated persistent nephrocalcinosis. During 30 months of follow-up, the patient exhibited normal neurodevelopmental progress but persistent challenges in growth, requiring endocrinology supervision. Laboratory parameters generally remained stable except for periodic hypercalciuria (Ca/Crea >0.3). Episodes of intercurrent infections led to rapid electrolyte deterioration, necessitating intensified monitoring and supplementation. Celecoxib therapy remained essential, with unsuccessful attempts at dose reduction. Nephrocalcinosis persisted without deterioration in renal function. This case highlights that early diagnosis of type I Bartter syndrome enables timely targeted therapy but achieving stable fluid, electrolyte, and nutritional status remains challenging. Long-term management requires multidisciplinary care, vigilant monitoring during intercurrent illnesses, and individualized adjustments in pharmacologic and nutritional therapy. This report contributes valuable longitudinal insight into the complexities of managing neonatal-onset Bartter syndrome.