Thyroid nodules are growths of cells in the thyroid glands. These growths can be benign (non-cancerous) or malignant (cancerous). Some nodules are fluid-filled (cysts), while others are completely made of thyroid gland cells. Sometimes, what feels like one nodule will actually be a collection of small nodules close together.
Thyroid nodules that are big enough to feel during a physical exam occur in 5 - 7% of the population. Smaller nodules occur in as many as 50% of people aged 60 or older. Thyroid nodules are more common in women than in men. A person's chance of a thyroid nodule increases with age.
Only 4 - 5% of thyroid nodules are cancerous. (See: Thyroid cancer)
The following characteristics increase the risk for a cancerous nodule:
Other risk factors for a cancerous nodule include:
Causes of thyroid nodules are not always found, but can include:
Most thyroid nodules produce no symptoms.
Large nodules can press against other structures in the neck. Symptoms may include:
Nodules that produce thyroid hormones will cause symptoms of hyperthyroidism, including:
Thyroid nodules resulting from Hashimoto's disease may cause symptoms of hypothyroidism, including:
Very often, doctors will find thyroid nodules only during a routine physical exam, because the nodules produce no symptoms. When a doctor finds a nodule, or when there are symptoms that suggest a nodule, your doctor may order the following tests:
Some thyroid nodules disappear without treatment. Surgery is recommended for nodules that:
Patients with working nodules sometimes receive treatment with radioactive iodine, which reduces the size of the nodule. However, the treatment can cause hypothyroidism and radiation-induced thyroiditis (inflammation of the thyroid gland). Pregnant women should not be given this treatment. Women being treated with radioactive iodine should not get pregnant.
Levothyroxine (Synthroid, Levoxyl, Levothroid, Unithroid) is a drug that suppress the production of the thyroid hormone T4. A doctor may prescribe levothyroxine to treat benign nodules only in special cases, including:
Levothyroxine does not seem to benefit most people with thyroid nodules, and can cause serious complications. Complications include heart problems and loss of bone density.
Careful follow-up is the only recommended treatment for benign nodules that do not cause symptoms and are not growing. A thyroid biopsy may need to be repeated 6-12 months after diagnosis. An ultrasound may be repeated as well.
Newer treatments include ethanol (alcohol) injection into the nodule and laser therapy.
Non-cancerous thyroid nodules are not life threatening. Many do not require treatment, only follow-up. Non-cancerous nodules that do require treatment have an excellent outlook.
The outlook for cancerous nodules depends on the type of cancer. See Thyroid cancer for more information.
Hyperthyroidism is a common complication of non-cancerous thyroid nodules. Complications of treatment can include:
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