Pattern of adrenal morphology and function in patients with acromegaly

Abstract

Acromegaly is well known to induce hypertrophic and hyperplastic changes in various organs and is commonly accompanied by arterial hypertension. In our study, we assess the adrenal morphology and function in a series of patients with acromegaly and possible associations with the activity of the disease and arterial hypertension. Sixty patients with acromegaly, admitted to two endocrinology departments in the time period 2005-2010, were studied prospectively. Basal IGF-1 and growth hormone levels after oral glucose tolerance test were used to assess the disease activity. All subjects underwent adrenal CT scan, basal adrenal hormonal investigation and evaluation with 24-h urinary free cortisol and cortisol levels following low-dose dexamethasone suppression test. In 33 acromegalics, the 'modified' saline infusion test (MSI), i.e. saline infusion after dexamethasone administration, was performed to identify autonomous aldosterone (ALD) secretion. Abnormal adrenal morphology was present in 48% of our patients, and a significant association was found between the presence of arterial hypertension and adrenal morphology. Among patients with adrenal morphological changes, 55% exhibited no adrenal secretory hyperactivity, 34% autonomous cortisol, 7% ALD and 4% combined autonomous cortisol and ALD secretion, when applying recently proposed modified cut-off levels compared to widely used criteria. An increased prevalence of autonomous ALD secretion was shown among the subgroup of patients with acromegaly tested with MSI. This study provides evidence of an increased prevalence of anatomic and functional adrenal alterations in patients with acromegaly; further studies will clarify the importance of evaluating these subjects with baseline hormonal investigation along with dynamic testing and modified cut-offs.