Endocrine Abstracts

Recent literature suggests anterior pituitary hormone deficiency (APHD) is common in paediatric patients with idiopathic cranial diabetes insipidus (CDI); this has been attributed to autoimmune panhypopituitarism.¹ We therefore determined the frequency of coexisting APHD and autoimmune disease in our cohort of patients with idiopathic adult CDI.

Eight patients with idiopathic CDI were reviewed (6 females mean age at diagnosis 30 years, range 7–46). Diagnosis was confirmed by failure to concentrate urine after water deprivation and good response to intramuscular dDAVP. T-1 weighted MRI showed loss of the posterior pituitary bright spot in all patients, and a thickened stalk in four patients. Anterior pituitary function was assessed with the insulin tolerance test (normal peak cortisol >500 nmol/l, normal peak GH >5 ng/ml) and basal hormone levels. One patient had hypogonadotrophic hypogonadism and partial GH deficiency (peak GH 3.4 ng/ml), but anterior pituitary function was normal in all other patients. Three patients had other autoimmune disease (Grave’s disease with pernicious anaemia 1, pernicious anaemia 2), and one was euthyroid with strongly positive thyroid antibodies, double the reported prevalence of 25%. Six patients had first degree relatives with autoimmune endocrine disease.

Anterior pituitary dysfunction occurred much less frequently in adult idiopathic CDI than previously reported in paediatric patients (16% vs 75%)¹ even though autoimmune endocrine disease was more frequent. Our data does not support recommendations for routine anterior pituitary function testing in idiopathic CDI¹ and we suggest that testing should based on appropriate clinical signs and symptoms in adult patients.

References

1. Maghnie M et al. Idiopathic central diabetes insipidus in children and young adults is commonly associated with vasopressin-cell antibodies and markers of autoimmunity. Clin Endo 2006 65(4) 470–478.