Endocrine Abstracts

Introduction: Central diabetes insipidus is a rare condition that typically manifests as polyuria-polydipsia syndrome. Polydipsia helps to maintain normal natremia. Herein, we report the case of persistent hypernatremia in a patient admitted for inaugural diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome.

Observation : A 53-year-old woman was referred to our department for inaugural diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome. Her past medical history included herpetic meningoencephalitis complicated by confusion, amnesia, and adipsia. On physical examination, she was apyretic, hemodynamically stable, and confused with signs of isolated extracellular dehydration. Laboratory investigations showed hyperglycemia at 30 mmol/l, hypernatrémie at 169 mmol/l with a plasma hyperosmolarity at 386.3 mOsm/l. The patient received rehydration with isotonic saline solution and insulin therapy. Ketosis was controlled with normalization of blood glucose. However, hypernatremia persisted (148-158 mmol/l) as much as the hyperosmolarity (321-336). Urine output was quantified at one liter/24h. Natriuresis was 54 mmol/l and urinary osmolarity was 205 mOsm/l suggesting hypotonicity. After administration of desmopressine, the natriuresis normalized and the urinary osmolarity rose to 743 mOsm/l. The diagnosis of central diabetes insipidus associated with adipsia was established and the patient was treated with desmopressine. The pituitary hormonal investigation showed isolated central hypothyroidism. Pituitary magnetic resonance imaging was normal.

Conclusion : Our case describes an uncommon presentation of central diabetes insipidus with no polyuria. The impaired sensation of thirst may be responsible for an atypical presentation of central diabetes insipidus called hypernatremia-hypodipsia syndrome.