IGF1 and thyroid tumor: Both IGF-1 and IGF-2 are produced locally in thyroid tumors, and several studies found that IGF-1 is positively correlated with thyroid volume, independently of age and body size, and studies have also shown that growth hormone (GH) / IGF-1 axis is associated with thyroid volume growth [25, 26].Whereas high serum IGF-1 levels are also related to thyroid nodule formation in men, they are related to decreased serum TSH levels in women [27].