Cause

Experts do not know the exact cause of thyroid nodules. But they do know that people who have been exposed to radiation have a greater chance of developing thyroid nodules. Exposure to environmental radiation or past radiation treatment to the head, neck, and chest (especially during childhood) raises your risk for thyroid nodules.

Experts know that thyroid nodules run in families. This means you are more likely to have a thyroid nodule if one of your parents has had a thyroid nodule.

Also, if you have another thyroid condition (such as goiter), you may have a greater chance of developing thyroid nodules.

Symptoms

Most thyroid nodules do not cause symptoms and are so small that you cannot feel them. They often are found during a physical exam or when another test, such as a CT scan or ultrasound, is done for a different reason.

If your thyroid nodule is big, you may be able to feel it or you may notice that your neck is swollen. In rare cases, you may also:

• Feel pain in your throat or feel like your throat is full.
• Have a hard time swallowing.
• Have a hard time breathing.
• Feel nervous, have a fast heartbeat, sweat a lot, lose weight, or have other symptoms of hyperthyroidism (too much thyroid hormone).
• Feel tired or depressed, have memory problems, be constipated, have dry skin, feel cold, or have other symptoms of hypothyroidism (too little thyroid hormone).