Thyroid gland changes in patients with acromegaly

Objective: Acromegaly is characterized by high neoplastic morbidity as a side effect of growth hormone (GH) hypersecretion. Increased incidence of goiter, thyroid carcinoma, and thyroid dysfunction is also reported. The aim of the present study was to find the prevalence of thyroid dysfunction and goiter in patients with acromegaly and determine its relationship to disease activity, disease duration, and the presence of secondary hypothyroidism. Subjects and methods: In a cross-sectional study of the period 2008-2012 were included 146 patients with acromegaly (56 men, 90 women) of mean age 50.3 +/- 12.4 years. Acromegaly disease activity and thyroid function were evaluated in all patients. Thyroid ultrasonography was performed to calculate thyroid volume and detect the presence of nodular goiter. Results: Ninety-one patients were determined to have an active disease, and 55, a controlled disease. The mean thyroid volume in patients without previous thyroid surgery was 37.6 +/- 38.8 mL. According to disease activity, thyroid volume was significantly higher in patients with active disease (38.5 +/- 45.4 mL vs. 27.2 +/- 18.4 mL, p = 0.036). A weak positive correlation was found between thyroid volume and insulin-like growth factor 1 (IGF-1) in the whole group and in females (R = 0.218; p = 0.013, and R = 0.238; p = 0.037, respectively). There was no significant correlation of thyroid volume with disease duration and GH level in the whole group and in both sexes. The patients with secondary hypothyroidism had twofold smaller thyroid volume, relative to the rest of the group. The prevalence of thyroid dysfunction was 39%, with a female to male percentage ratio of 1.73. Goiter was diagnosed in 87% of patients, including diffuse goiter (17.1%) and nodular (69.9%), with no significant difference between patients with active and controlled disease or the presence of secondary hypothyroidism. Conclusions: Thyroid volume in patients with acromegaly depends on disease activity and the presence of secondary hypothyroidism as a complication. The increased prevalence of nodular goiter determines the need of regular ultrasound thyroid evaluation in the follow-up of patients with acromegaly.