You are older. Thyroid nodules are more common
in older people.
You are female. Women are more likely than men to
develop thyroid nodules.
You have been exposed to radiation.
Exposure to environmental radiation or past
radiation treatment to your head, neck, and chest
(especially during childhood) increases your risk for thyroid nodules.
You do not get enough iodine. Iodine deficiency is rare
in the United States, but it is common in areas where iodine is not added to
salt, food, and water. An iodine deficiency may result in an enlarged thyroid
gland (goiter), with or without nodules.