LAUSR

Abstract Introduction: The incidence of diabetes insipidus (DI) in pregnancy is rare, affecting 2 to 4 cases per 100,000 gestations. Management of pregestational DI poses a challenge for patients who are already on 1-deamino-8-D-arginine vasopressin (desmopressin acetate) (DDAVP) as limited data is available on DDAVP adjustments during pregnancy. This case series describes three patients with pregestational central DI, all of whom required increased DDAVP doses during pregnancy. Case Presentation; Case 1: A 28 year old female with central DI from Langerhans cell histiocytosis was maintained on DDAVP nasal spray 10 mcg twice daily. At 16 weeks gestation, she reported symptoms of polyuria and polydipsia and DDAVP was increased to 20 mcg twice daily. Urine osmolality trended down by 67% (146 mOsm/kg) at 24 weeks gestation but serum sodium (136-143 mmol/L) remained in normal range. Case 2: A 30 year old female with central DI from a concussion was maintained on DDAVP tablet 50 mcg twice daily. Increased polydipsia was reported within the first trimester, however self-reported polyuria occurred at 23 weeks. At this time DDAVP was increased to150 mcg. Urine osmolality trended down by 52% at 27 weeks gestation (237 mOsm/kg) while serum sodium (134-137mmol/L) remained stable. Case 3: A 34 year old female with congenital central DI was maintained on DDAVP tablet 300 mcg total daily dose. During her first pregnancy DDAVP was increased to 500 mcg at 10 weeks gestation due to polyuria and polydipsia. During her second pregnancy DDAVP was increased to 600 mcg at 18 weeks gestation. Serum sodium levels (135-138 mmol/L) in second pregnancy remained stable in normal range. Post-partum, all three patients resumed pre-pregnancy DDAVP dose. Discussion: Although the development and management of gestational DI is reviewed in several papers, there is limited information on the management of pregestational central DI in pregnancy. Physiologic changes in water homeostasis predispose pregnant women to developing symptoms of polyuria and polydipsia. It may therefore be difficult to determine if worsening symptoms are related to inadequate DDAVP dosing. Patients with pregestational central DI can perceive worsening symptoms as early as the first trimester. DDAVP doses increased by 25-100% between the second and third trimester correlating with a decline in urine osmolality by 53-67% in two of our patients. Serum sodium levels remained in normal range. Our goal is to share our clinical experience with managing pregestational DI in pregnancy. It is important to be aware of the physiological changes and how they correlate with fluctuations in DDAVP requirements. Additional standardization regarding the management of pregestational DI would be beneficial for future pregnancy cases, however this may be difficult to achieve due to the rarity of the condition.