Clinical and diagnostic complexities of adipsic arginine vasopressin deficiency

Adipsic arginine vasopressin deficiency (AAVP-D) is a rare hypothalamic disorder, with inadequate vasopressin production and impaired thirst, resulting in sodium and water dysregulation. It poses multiple challenges, including increased morbidity and mortality. We present a 24-year-old female who developed confusion after neurosurgical debulking of a central neurocytoma. Investigations revealed hypernatremia alongside raised plasma osmolality, low urine osmolality, polyuria, and adipsia. Transient AAVP-D was suspected; it was successfully treated with intravenous desmopressin, which resolved predischarge. One week later, she re-presented to the hospital with confusion. Recurrence of hypernatremia, plasma hyperosmolality, and polyuria occurred and permanent AAVP-D was suspected. She was commenced on oral desmopressin 50 mcg/day, titrated to 150 mcg/day, with strict oral fluid regime of 2 L/day. She remains adipsic 24 months postoperatively. Her case highlights the multiple challenges of AAVP-D. Management includes calculating a daily fluid intake goal and titration with desmopressin to ensure consistent urine output, patient weight, and plasma sodium levels with careful outpatient monitoring.