Risk Factors Associated with Thyroid Nodules or Tumors

You are more likely to develop a thyroid nodule if:

• 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.
• You have Hashimoto's thyroiditis. Hashimoto's thyroiditis can cause an underactive thyroid gland (hypothyroidism).
• One or both of your parents have had thyroid nodules.

Most thyroid nodules are not cancerous. But a nodule is more likely to be cancerous if:

• You have had radiation treatment, or you were exposed to radiation in the environment. In rare cases, thyroid cancer could appear up to 20 years after radiation exposure.
• You have family members who have had cancer in their endocrine glands, including the thyroid gland.
• You are younger than 30 or older than 60.
• You are male.
• The nodule grows quickly over a period of weeks or months. But just because a nodule has changed in size does not mean it is cancerous.
• You develop a nodule while you are pregnant.
• You have Graves' disease.
• You have Hashimoto's thyroiditis. Hashimoto's thyroiditis can cause an underactive thyroid gland (hypothyroidism).
• One or both of your parents have had thyroid nodules.

Most thyroid nodules are not cancerous, but a thyroid nodule is more likely to be cancerous if:

You have had radiation treatment, or you were exposed to radiation in the environment. 

In rare cases, thyroid cancer could appear up to 20 years after radiation exposure.

You have family members who have had cancer in their endocrine glands, including the thyroid gland.

You are younger than 30 or older than 60.

You are female (Women and girls are three times more likely to be diagnosed with thyroid cancer)

The thyroid nodule grows quickly over a period of weeks or months. 

You develop a thyroid nodule while you are pregnant.

You have Graves' disease.

You have Hashimoto's thyroiditis.