Thyroid autoimmune disorders in patients with acromegaly

Disorders of the hypothalamic-pituitary-thyroid axis are common in patients with acromegaly and thyroid enlargement is present in the majority of them. The exact prevalence of goiter in patients with acromegaly remains uncertain and the presence of thyroid autoimmunity has not been extensively evaluated so far.

We retrospectively evaluated thyroid biochemical and morphological findings in 116 acromegalic patients who attended our hospital. Serum TSH, total thyroxine levels and anti-thyroid peroxidase (ATPO) antibodies were measured by standard ultrasensitive techniques in all the patients. Thyroid ultrasound was performed in 75 out of them. The antibody control group was composed by healthy Argentinean individuals who attended the blood bank of our hospital in whom ATPO antibodies were measured.

Twenty-nine out of the 116 acromegalic patients (25 %) showed elevated titers of thyroid antibodies (79 % were women and 21 % men). The control group had a 10 % prevalence of thyroid autoimmunity. The prevalence of goiter by ultrasound was 36 %, being more common in females (41 %) than in males (28 %). Thirty-five percent of patients who presented thyroid nodules and 44 % of patients with ultrasound diagnosed goiters had positive thyroid autoimmunity. There was no significant correlation between the presence of nodules and IGF-1 levels, duration of disease or age.

We found a high prevalence of thyroid autoimmunity in our patients with acromegaly as compared to the normal population. Thyroid autoimmunity seems to be an additional mechanism for the development of thyroid disorders in acromegaly.