@article {Otsuboe242086, author = {Yuto Otsubo and Yuji Kano and Hiroshi Suzumura and Shigemi Yoshihara}, title = {Type 3 antenatal Bartter syndrome presenting with mild polyuria}, volume = {14}, number = {4}, elocation-id = {e242086}, year = {2021}, doi = {10.1136/bcr-2021-242086}, publisher = {BMJ Specialist Journals}, abstract = {Bartter syndrome (BS) is a well-recognised inherited tubular dysfunction that causes polyuria, metabolic alkalosis and hypokalaemia. Among BS cases, antenatal/neonatal BS (ABS) usually shows distinct polyhydramnios prenatally and presents features of BS in the early neonatal period. We encountered a premature infant with type 3 ABS presenting with mild polyuria and discuss the pathogenesis of mild polyuria in type 3 ABS. A male infant was born at 31 weeks{\textquoteright} gestation. His mother received amniocentesis because of polyhydramnios. Hyponatraemia and hypokalaemia appeared within 3 days after birth. Metabolic alkalosis, hyperreninaemia and hyperaldosteronism were also identified. Temporary polyuria developed at 1 month after birth; however, the mean urine output during hospitalisation was within the normal range. CLCNKB compound heterozygous mutations were confirmed. Polyuria of type 3 ABS may be less severe than in other types of ABS. Lower urine sodium loss may be a characteristic feature of type 3 ABS.}, URL = {https://casereports.bmj.com/content/14/4/e242086}, eprint = {https://casereports.bmj.com/content/14/4/e242086.full.pdf}, journal = {BMJ Case Reports CP} }