Endocrine Abstracts

Introduction: Gestational diabetes insipidus (GDI) is a rare complication of pregnancy thought to be due to increased vasopressin produced by the placenta. It usually occurs at the end of the second or in the third trimester.

Case Description: We report the case of a 28-year-old female patient, a primigravida with a previous history of Right hemi-anomalous pulmonary venous drainage into IVC with an initial baffle operation in October 2019. She had diet-controlled gestational diabetes mellitus and was not on any medications. During the 34^th gestational week, she was admitted to the hospital with a 6-week history of polyuria and polydipsia associated with haematuria. On the admission day urine output over 12 hours was 7740 ml. Initial investigation showed:MRI Pituitary: No pituitary or infundibula abnormality. Minor focal T2 signal dropout around the hypothalamus may represent an old area of microhaemorrhage but does not appear acute. Urine input per 24 hours was more than 10000 ml. She underwent the water deprivation test two days after the admission. She remained polyuric throughout the test with a weight loss of approximately 3 Kg. She was unable to concentrate urine throughout the test with urine osmolality not rising >30 mosm/kg. Urine osmo improved after DDAVP 1 mg s/c stat (108 -- > 288 mosm/kg). She was started with sublingual Desmopressin 50 mg twice a day which improved the urine output. Her Sodium remained within the normal range. She was discharged from the hospital on Desmopressin 100 mg once daily. She delivered a healthy baby with no complications. She was reviewed 8 weeks post-delivery, and she remains polyuric despite taking sublingual Desmopressin 100 mg at bedtime.

Conclusion: Polyuria is often dismissed as a normal symptom in pregnancy; however, it is important to recognize that it may indicate pregnancy-related DI, as this condition may lead to serious consequences for both the patient and the fetus.