The effect of disease activity on thyroid nodules in patients with acromegaly

Nodular thyroid disease is a very common disorder in patients with acromegaly. Insulin-like growth factor-1 (IGF-1) is a thyroid growth factor, and there is a correlation between IGF-1 levels and thyroid volume (TV) in patients with acromegaly. There is no study investigating the impact of somatostatin analog (SSA) treatment on thyroid nodule volume in patients with acromegaly. We aimed to assess thyroid nodule volume change with SSA treatment in patients with persistent acromegaly. We retrospectively analyzed data from 108 consecutive patients with acromegaly who were followed up by our clinic after undergoing surgery between 2002 and 2014. Patients who were cured after surgery were excluded. We only selected 43 patients (21 males, 22 females, mean age 52.8 ± 11.9 years) who did not meet the criteria of remission postoperatively, who were treated with SSA for at least six months and had normal thyroid function. Patients were divided into three groups (well-controlled, controlled, and active) according to their IGF-1 and growth hormone (GH) levels. All patients underwent an evaluation of TV and total thyroid nodule volume (TTNV) by ultrasound. TTNV decreased significantly in patients with well-controlled acromegaly (0.44 [0.75] to 0.23 [0.73], p < 0.001). TTNV did not change in controlled patients (0.18 [1.28] to 0.13 [1.54], p = 0.959); however TTNV increased in patients with active acromegaly (0.77 [1.46] to 1.03 [1.88], p = 0.028). Successful medical treatment of patients with active acromegaly decreases thyroid nodule volume. Sustained exposure to IGF-1 may cause an increase in thyroid nodule volume in patients with acromegaly.