A Rare Case of Hyponatremia Caused by Reset Osmostat in a Neonate with Cleft Lip, Cleft Palate, and Imperforate Anus

Jung Gu Ahn, Jeong Eun Lee, Woo Yeong Chung, Soo Hyun Koo, Jaeho Shin, Ga Won Jeon
2018 Neonatal Medicine  
Hyponatremia is defined as a plasma sodium concentration of <135 mEq/L. It is a common electrolyte imbalance in newborns. We report the case of a term neonate with cleft lip, cleft palate, imperforate anus, normal male karyotype, and chronic hy ponatremia. On the 4th day of life, he showed hyponatremia (plasma sodium concen tration 130 mEq/L) with low serum osmolality (275 mOsm/kg), high urine sodium (116.7 mEq/L), and high urine osmolality (412 mOsm/kg). His thyroid and adrenal functions were
more » ... ormal. Despite intravenous and oral sodium supplementation and hydrocortisone treatment, hyponatremia persisted. Brain magnetic resonance imag ing showed normal results. He was diagnosed as having reset osmostat, a rare subtype of the syndrome of inappropriate secretion of antidiuretic hormone characterized by a subnormal threshold for antidiuretic hormone secretion, with hypotonic hypona tremia.
doi:10.5385/nm.2018.25.3.131 fatcat:dgt5tpjmnrby3agcu4q64tbqce