Endocrine Abstracts

Cranial Diabetes Insipidus is a rare diagnosis and rarer still postpartum. We present the case of 24-year-old woman who developed CDI following pregnancy. The patient had developed polydipsia and polyuria 5 months following pregnancy. The pregnancy had been complicated by Gestational Diabetes Mellitus and a large Postpartum Haemorrhage. The patient reported feeling fatigued, lightheaded and she stated a need to drink water frequently: ~ 8 litres throughout the day and 4 litres overnight. She reported being unable to breastfeed but was otherwise well: she attributed her symptoms of lethargy to sleepless nights with her new born baby, the polyuria as a consequence of vaginal delivery and as such presented for initial review 18 months following delivery. Investigations revealed a fasting blood glucose of 4.9 mmol/l, an Adj. Calcium of 2.23 mmol/l and a fasting urine osmolality of 85 mmol/kg. A diagnosis of DI was suspected and was confirmed by water deprivation test: the patient had an inappropriately dilute urine osmolality of 111 mmol/kg when compared to the serum osmolality of 301 mOsm/Kg at the start of the test and her urine failed to concentrate as water was withheld. Administration of DDAVP resulted in appropriate concentration of urine confirming the diagnosis specifically as Cranial Diabetes Insipidus. The patient was established on DDAVP replacement therapy and her quality of life improved: she enjoyed restful sleep and reported less exhaustion. There was no anterior pituitary hormone deficiency 28 months following delivery. MRI Pituitary revealed an unusually flat and broad pituitary gland with a possible tiny lesion in the posterior pituitary suggestive of an adenoma. DI is a rare diagnosis with an estimated prevalence of 1 in 25 000 people. CDI has been commonly reported as being caused by infiltrative or inflammatory pituitary disease, as an iatrogenic sequelae of pituitary surgery or as a result of a congenital defect in the production of vasopressin. We suspect that in this case the patient’s PPH may have resulted in isolated cranial diabetes insipidus though the significance of the MRI scan findings remains unclear. This case highlights that CDI can occur following pregnancy in an isolated form without anterior pituitary hormone deficiency and that patients may misattribute significant symptoms and signs of DI as being a normal part of the postpartum period resulting in a delayed diagnosis.