Anterior hypopituitarism is rare and autoimmune disease is common in adults with idiopathic central diabetes insipidus

Objective Central diabetes insipidus is a rare clinical condition with a heterogenous aetiology. Up to 40% of cases are classified as idiopathic, although many of these are thought to have an autoimmune basis. Published data have suggested that anterior hypopituitarism is common in childhood‐onset idiopathic diabetes insipidus. We aimed to assess the incidence of anterior hypopituitarism in a cohort of adult patients with idiopathic diabetes insipidus. Design and patients We performed a retrospective review of the databases of two pituitary investigation units. This identified 39 patients with idiopathic diabetes insipidus. All had undergone magnetic resonance imaging scanning and dynamic pituitary testing (either insulin tolerance testing or GHRH/arginine and short synacthen testing) to assess anterior pituitary function. Results One patient had partial growth hormone deficiency; no other anterior pituitary hormonal deficits were found. Thirty‐three percent had at least one autoimmune disease in addition to central diabetes insipidus. Conclusions Our data suggest that anterior hypopituitarism is rare in adult idiopathic diabetes insipidus. Routine screening of these patients for anterior hypopituitarism may not, therefore, be indicated. The significant prevalence of autoimmune disease in this cohort supports the hypothesis that idiopathic diabetes insipidus may have an autoimmune aetiology.