Endocrine Abstracts

Background: Insulin-like growth factor-1 (IGF-1) is known to be closely related to the growth of thyroid cells and thyroid diseases. However, the association between IGF-1, thyroid nodule, and thyroid cancer has not been clearly established yet. Therefore, this study investigated the association between IGF-1 and thyroid nodule size.

Methods: A total of 346 patients with thyroid nodules confirmed by ultrasonography were included. For all participants, the levels of serum T3, free T4, TSH and IGF-1, were determined by radioimmunoassay. Among the participants, the risk group was defined as those with nodule size greater than 10mm or those with suspicious features on ultrasonography even for nodule size smaller than 10mm, and they underwent fine needle aspiration biopsy. The measurement data were expressed as the mean ± standard deviation (S.D.). The analysis of variance was performed by t-test, and the correlation analysis was performed by linear regression.

Results: The proportion of patients with large nodule size and suspicious sonographic features was significantly higher in risk group. In non-risk group, IGF-1 and nodule size did not show a significant association. Subgroup analysis for the risk groupfound IGF-1 to be significantly elevated in subjects whose cytology returned as thyroid cancer. (173.3 ng/ml vs 213.1ng/ml, P-value <0.05). In this group, IGF-1 and nodule size demonstrated a positive association (r=0.195, P-value <0.05), and multiple linear regressions found IGF-1 to be independently associated with nodule size.(ß=5.579, P-value <0.05)

Conclusions: A positive association between IGF-1 and nodule size was observed only in risk group, and IGF-1 was elevated in thyroid cancer group. Measuring serum IGF-1 in patients with large thyroid nodule on ultrasonography and with suspicious sonographic features may be clinically significant.