FRI353 Diabetes Insipidus - Pituitary Apoplexy Or Placental Vasopressinase?

Disclosure: N.M. Rodrigues: None. J. Palacios Merchan: None. M.B. Twahirwa: None. Background: Pituitary apoplexy is rare in pregnancy. Diabetes insipidus is rare at apoplexy onset, present in about 5% of patients presenting with apoplexy. Gestational DI can occur due to placental vasopressinase though this is more common in twin pregnancies and pre-eclampsia. Clinical Case: 28-year-old Hispanic woman was admitted at 34-weeks' gestation for 1 week of headache, visual symptoms, elevated blood pressure and polyuria. Her thirst was intact. She had a known history of 8 mm prolactinoma, which was diagnosed 2 years prior to admission. She was treated with Cabergoline 0.5 mg twice weekly, which was stopped once pregnancy was confirmed. A 24-hour urine collection was performed as part of her pre-eclampsia workup. Total volume was 11,250 mL, osmolality 97 mOsm/kg and sodium of 25 mmol/L. Serum sodium was 136 mmol/L. MRI of the brain showed pituitary apoplexy with large suprasellar area hemorrhage, compressing the pituitary gland and infundibulum, resulting in anterior displacement. The optic chiasm was also compressed and displaced superiorly. Her BP remained normal throughout admission and pre-eclampsia workup was negative. Lab work did not show significant hypopituitarism with TSH of 1.3 microIU/mL, Free T4 0.53 ng/dL, random Cortisol of 11.5 mcg/dL, IGF-1 167 ng/mL, Copeptin 3.8 pmol/L. Considering this was the third trimester of pregnancy as well as the chronicity of the bleed, thought to be 5-7 days, neurosurgery suggested conservative management. She continued to maintain normal serum sodium levels throughout admission. She was delivered at 35 weeks by Caesarean section. She received Hydrocortisone 100 mg IV before the surgery. She also received DDAVP 1 mcg IV before delivery since her sodium level increased to 145 mmol/L from a baseline of 133-136 mmol/L. The delivery was uneventful, and she had a healthy baby. After delivery, her urine output decreased to 180 cc/hour with significant improvement in thirst. Her serum sodium remained normal. This raises the question of whether DI was due to apoplexy or placental effect. Conclusion: Even though pregnancy causes hypertrophy of the lactotrophs, pituitary apoplexy is less common in microadenomas. Apoplexy in pregnancy is very rare, occurring only in 1 in 10,000 gestations. The clinical presentation in this case suggests a low threshold to order pituitary imaging in cases presenting with concerning sign symptoms of increase intracranial pressure. Guidelines are limited in the management of pituitary apoplexy in pregnancy. There are case reports and case series where patients with apoplexy were delivered with C- section at 34 weeks. In addition, the element of pregnancy induced DI makes this presentation unique. Presentation: Friday, June 16, 2023