MON-034 Postpartum Diabetes Insipidus: A Report of Four Cases

Abstract Disclosure: H. Noto: None. M. Hiranuma: None. A. Tamayose: None. M. Tonoike: None. Introduction: We here report rare 4 cases of pregnancy-related diabetes insipidus (DI) which developed after a few days postpartum and have been persisting for more than several months. Case 1: a 35-year Japanese woman (G1P0) who was complicated with gestational diabetes mellitus (GDM) and pregnancy-related hypertension developed polyuria (10 L/day) and polydipsia after 3 days postpartum. The blood loss during delivery was 2000 grams. The initial tests showed serum sodium 142 mmol/L, osmolality 286 mOsm/kg, antidiuretic hormone (ADH) 0.9 pg/mL, and urinary osmolality 199 mOsm/kg. The result of endocrinological work-up (hypertonic saline stimulation test followed by desmopressin administration) confirmed the diagnosis of central DI. The result of pituitary MRI was consistent with lymphocytic infundibulo-neurohypophysitis. Case 2: a 44-year Japanese woman (G6P1) who was complicated with GDM and pregnancy-related hypertension developed polyuria (6 L/day) and polydipsia after 2 days postpartum. The blood loss during delivery was 615 grams. The initial tests showed serum sodium 139 mmol/L, osmolality 282 mOsm/kg, ADH 0.9 pg/mL, and urinary osmolality 410 mOsm/kg. The result of endocrinological work-up confirmed the diagnosis of central DI. The result of pituitary MRI was consistent with lymphocytic infundibulo-neurohypophysitis. Case 3: a 32-year Japanese woman (G2P0) who was complicated with GDM developed polyuria (4 L/day) and polydipsia after 2 days postpartum. The blood loss during delivery was 975 grams. The initial tests showed serum sodium 141 mmol/L, osmolality 285 mOsm/kg, ADH 0.7 pg/mL, and urinary osmolality 195 mOsm/kg. The result of endocrinological work-up confirmed the diagnosis of central DI. The result of pituitary MRI was unremarkable. Case 4: a 34-year Japanese woman (G1P0) who was complicated with pregnancy-related hypertension developed polyuria (>3L/day) and polydipsia after 2 days postpartum. The blood loss during delivery was 1314 grams. The initial tests showed serum sodium 142 mmol/L, osmolality 287 mOsm/kg, ADH 1.0 pg/mL, and urinary osmolality 242 mOsm/kg. The result of endocrinological work-up confirmed the diagnosis of central DI. The result of pituitary MRI was unremarkable. Discussion: All the patients have been treated with intranasal vasopressin preparation with a good control of symptoms, urine output and electrolytes, but none of them has recovered from DI completely. Gestational DI is an uncommon complication during pregnancy, occurring in about one in 30,000 pregnancies. This condition generally manifests in the third trimester and usually resolves spontaneously within 4 to 6 weeks after childbirth. Our cases of postpartum DI, which is extremely rare, point to the possibility that DI may occur postpartum and persist, and illustrate the importance of prompt diagnosis and appropriate treatment to prevent life-threatening outcome. Presentation: Monday, July 14, 2025