Adrenal lesions in acromegaly: do metabolic aspects and aryl hydrocarbon receptor interacting protein gene have a role? Evaluation at baseline and after long-term follow-up.

Background: Adrenal lesions are discovered in acromegaly more frequently than in general population, without relationship with primary disease. Some patients, carriers of aryl hydrocarbon receptor interacting protein (AIR) gene mutations, developed an adrenal neoplasm. Aim: To evaluate the role of metabolic and genetic aspects and the follow-up of adrenal nodules in acromegaly. Material and methods: We studied 69 acromegalic patients (30 male and 39 female, 56 +/- 15 yr) who had been referred to the Endocrinology Unit of Padua. In all patients we determined body mass index (BMI) and waist-to-hip ratio (WHR); we performed an oral glucose tolerance test (OGTT) whenever possible. If adrenal computed tomography revealed a lesion, the patient underwent an endocrine and genetic study. Results: Adrenal lesions were identified in 14 patients and were not related to gender, duration of disease, GH or IGF-I concentrations, basal and after-OGTT glucose and insulin levels, log(HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI) values, whereas BMI and WHR were higher in patients with adrenal lesions. Baseline endocrine and radiological study revealed benign lesions; during mean 4-yr follow-up none of the patients showed hormone excess, even though some lesions increased in size. We did not find any mutation in AIP gene, except heterozygous silent alteration (T48T). Conclusions: The frequency of non-functioning adrenal lesions in acromegaly is not associated with the considered aspects, except BMI and WHR. The prolonged follow-up showed that these lesions have a tendency to increase in size independently of the control of acromegaly, so a morphological follow-up is recommended.