PT  - JOURNAL ARTICLE
AU  - Yuto Otsubo
AU  - Yuji Kano
AU  - Hiroshi Suzumura
AU  - Shigemi Yoshihara
TI  - Type 3 antenatal Bartter syndrome presenting with mild polyuria
AID  - 10.1136/bcr-2021-242086
DP  - 2021 Apr 01
TA  - BMJ Case Reports
PG  - e242086
VI  - 14
IP  - 4
4099  - http://casereports.bmj.com/content/14/4/e242086.short
4100  - http://casereports.bmj.com/content/14/4/e242086.full
SO  - BMJ Case Reports2021 Apr 01; 14
AB  - 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’ 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.