Who do thyroid nodules affect?

Anyone can have a thyroid nodule, including children and adults. However, they’re about four times more common in people assigned female at birth than people assigned male at birth.

They also occur more often in people who live in countries in which food isn’t fortified with iodine. (Iodine is necessary for your thyroid gland to make hormones.)

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Other factors that lead to an increased risk of thyroid nodules include:

• History of thyroid radiation.

• Family history of thyroid nodules or thyroid cancer.

• Increasing age.

• Iron-deficiency anemia.

• Smoking.

• Obesity.

• Metabolic syndrome.

• Alcohol consumption.

• Increased levels of insulin-like growth factor-1 (a hormone).

• Uterine fibroids.

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How common are thyroid nodules?

Thyroid nodules are common. Healthcare providers detect them in approximately 5% to 7% of adults during a physical examination. Ultrasound imaging reveals that 20% to 76% of adults have thyroid nodules.

Thyroid nodules are less common in children.

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What symptoms can thyroid nodules cause?

Most thyroid nodules don’t cause symptoms. However, if you have several nodules or large nodules, you may be able to see them.

In rare cases, nodules can grow big enough to cause the following symptoms:

• Trouble with swallowing or breathing.

• Hoarseness or voice changes.

• Pain in the front of your neck.

• Enlargement of your thyroid gland (goiter).

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Hyperfunctioning thyroid nodules can lead to overproduction of thyroid hormones, also known as hyperthyroidism. Symptoms of hyperthyroidism include:

• Rapid heartbeat (palpitations).

• Feeling shaky and/or nervous.

• Weight loss.

• Increased appetite.

• Diarrhea and more frequent bowel movements.

• Difficulty sleeping.

• Enlarged thyroid gland (goiter).

• Light or missed menstrual periods.

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Thyroid nodules may also be associated with low thyroid hormone levels (hypothyroidism). Symptoms of hypothyroidism include:

• Fatigue.

• Numbness and tingling in your hands.

• Weight gain.

• Dry, coarse skin and hair.

• Constipation.

• Depression.

• Frequent, heavy menstrual periods.

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What causes thyroid nodules?

Researchers don’t know why most thyroid nodules form. Nodules can form for various reasons, and there are different types, including:

• Colloid nodules: These are one or more overgrowths of normal thyroid tissue. These growths are not cancer (benign). They may grow large, but they don’t spread beyond your thyroid gland. These are the most common type of thyroid nodules.

• Thyroid cysts: These are growths that are filled with fluid or are partly solid and partly filled with fluid. Cystic nodules pose a low risk for cancer (malignancy) and are either monitored or biopsied if they’re larger than 2 centimeters.

• Inflammatory nodules: These nodules develop as a result of long-term (chronic) swelling (inflammation) of your thyroid gland. These growths may or may not cause pain.

• Multinodular goiter: Sometimes an enlarged thyroid (goiter) is made up of many nodules (which are usually benign).

• Hyperfunctioning thyroid nodules: These nodules produce extra thyroid hormone, which may lead to the development of hyperthyroidism. Hyperthyroidism requires treatment.

• Thyroid cancer: Cancer is the biggest concern when thyroid nodules form. Fortunately, thyroid cancer is very rare — it’s found in less than 6.5% of all thyroid nodules.