Isolated secondary adrenal insufficiency - an underestimated consequence of asymptomatic autoimmune hypophysitis

Abstract

We read with great interest the paper by Trevor A. Howlett et al. on autoimmune hypophysitis and we found it very important for management of this disorder. Autoimmune hypophysitis with clinical features of a pituitary mass is a rare event. We believe that a subclinical form of this disease is much more frequent in clinical practice. We have in our observation a group of 305 patients with idiopathic isolated secondary adrenal insufficiency. Interestingly, 203 (67%) of them had associated various autoimmune disorders. Apart from the well-known hypothalamic-pituitary-adrenal suppression because of exogenous corticosteroids, only an autoimmune mechanism is able to influence selectively the secretory function of the corticotrophs in adult patients. The most frequent finding in MRI of our patients was partially empty sella turcica, probably as a consequence of asymptomatic autoimmune hypophysitis. Thyroid autoimmune diseases, both hypothyroidism and thyrotoxicosis, as well as Hashimoto’s disease without apparent clinical manifestations, were the most frequent autoimmune disorders in this group of patients. Vitiligo, premature ovarian failure, type 1 diabetes mellitus and pernicious anaemia were also rather frequently observed. Coexistence of these autoimmune abnormalities and antipituitary antibodies detected in some of the tested cases 5 suggested adrenocorticotrophic hormone deficiency of autoimmune origin. By all means, in our patients, there was no indication to perform pituitary biopsy. In our experience, it is very important to diagnose correctly patients with idiopathic isolated secondary adrenal insufficiency because some of them are falsely treated as gastroenteritis in situation of an imminent adrenal crisis.