Risk factors associated with thyroid nodular disease in acromegalic patients: A case-cohort study in a tertiary center.

INTRODUCTION: Goiter is very common in patients with acromegaly; its development is correlated to the duration of the disease. Thyroid cells express the IGF-1 receptor and the TSH/IGF-1 interaction has been demonstrated to have a synergistic effect in thyroid cell growth. There is a correlation between IGF-1 levels and the thyroid volume of patients with acromegaly. The aim of this study was to evaluate, in a retrospective case-cohort study of patients with acromegaly, the associated risk factors for thyroid nodules disease in this population. METHODS: This was a case-cohort study matched by age, gender, and growth hormone at diagnosis. Cases consisted of acromegalic patients that developed thyroid nodules during the follow up, and controls consisted in acromegalic patients without thyroid nodules. A Cox proportional hazard estimation was carried out for measure the associated risk factors for thyroid nodules disease in acromegalic patients. A nodular thyroid disease-free survival analysis was estimated using the Kaplan-Meier analysis. RESULTS: We recruited 49 cases and 56 controls. In a multivariate Cox proportional hazard analysis age and IGF-1 ≥ 2.2 x ULN were significantly related with the presence of thyroid nodules [HR of 2.21 (95% CI; 1.15-4.25, p = 0.01)]. Nodularity-free survival rates in patients who had an IGF-1 X ULN ≥ 2.2 was found to be lower in comparison to those who had IGF-1 X ULN < 2.2, according to a Kaplan-Meier survival analysis. CONCLUSIONS: Our findings support that exist more probability to develop thyroid nodular disease in patients with acromegaly that present IGF-1 X ULN ≥ 2.2, suggesting a possible direct effect between the time of exposure to the IGF-1 axis hyperactivity and the genesis of thyroid nodules.