SUN-284 Rare Case of Adipsic Diabetes Insipidus Post Astrocytoma Resection: Case Report

Background: Adipsic diabetes insipidus (ADI) is a rare disorder triggered by injury to the hypothalamus impairing thirst osmoreceptors and the antidiuretic hormone syntheses leading to absence of thirst. We are reporting a rare case of ADI Post astrocytoma resection who presented with a severe hypernatremia postoperatively. Clinical Case: A 16-year-old female known to have hypothalamic pilocystic astrocytoma post incomplete resection in 2014. She presented in 2018 with one week history of sudden onset heachache, progressively worsen overtime, worst in the morning, there were no relieving factors. On examination she was conscious alert oriented GCS 15/15, Vital signs were normal, fundus exam within normal, pupil equal bilateral reactive to light, there was no focal neurological deficit. Systemic examination was unremarkable. Radiological imaging revealed interval size progression of previously seen suprasella region with extension into the floor of the third ventricle. Investigations: Renal profile & pituitary hormonal profile were normal. She underwent second stage resection. Postoperatively, she developed asymptomatic hypernatremia with inability to sense thirst. On examination: Conscious, alert, BP:100/65, no postural drop, Pulse:95, Fluid balance negative 1L. Systemic examination was unremarkable. Laboratory investigations: Creat 0.77mg/dl (0.6–1), Na 173mEq/dl(136–145), K 3.3mEq/dl(3.5–5.1), Cl 134mEq/dl(98–107), Serum osmolality 363mOs/kg(285 -295), Urine osmolality 468mOs/kg(300 -1600), Urine Na 29mEq/L(20- 110) & Urine volume 1900. Diagnosis of ADI was made where she was treated with desmopressin. Her response was good with reduction in Na level of around 7- 9 mEq/L/Day. She was maintained on twice daily vasopressin, instructed to maintain her fluid intake 1–1.5 L/day and good urine output. Conclusions: Astrocytoma rarely linked with development of central diabetes insipidus and even fewer with adipsia. The absence of polydipsia and polyuria can be misleading. Long-term therapy should consider the benefits of vasopressin and fluid therapy against the risk of brain edema/herniation. Body weight and electrolytes monitoring essential & should be maintained a long with strict fluid intake.