Reset Osmostat in Chronic Hyponatremia: Physiology, Diagnosis, and Links to Congenital Midline Brain Malformations (with an illustrative case of Corpus Callosum Agenesis)

Güvercin B., Zaman B. B., Can M., Ulusoy Ş.

medical science and dıscovery , cilt.13, sa.3, ss.45-50, 2026 (Hakemli Dergi)

  • Yayın Türü: Makale / Derleme
  • Cilt numarası: 13 Sayı: 3
  • Basım Tarihi: 2026
  • Dergi Adı: medical science and dıscovery
  • Derginin Tarandığı İndeksler: Index Copernicus
  • Sayfa Sayıları: ss.45-50
  • Karadeniz Teknik Üniversitesi Adresli: Evet

Özet

 Reset osmostat (RO) is an under-recognized disorder of osmoregulation characterized by a downward resetting of the plasma osmolality threshold for arginine vasopressin release. Affected individuals develop chronic, typically mild and stable hypotonic hyponatremia while preserving the ability to dilute urine and excrete a water load. Because RO is frequently misclassified as the syndrome of inappropriate antidiuresis (SIAD), patients may undergo unnecessary investigations and receive potentially harmful therapies aimed at normalizing serum sodium. To summarize the physiology of the osmostat, identify clinical contexts associated with RO—including congenital midline brain malformations—and highlight practical diagnostic features that distinguish RO from SIAD and other causes of euvolemic hyponatremia.