What are thyroid nodules?
A thyroid nodule is an unusual growth (lump) of thyroid cells in the thyroid gland.
Most thyroid nodules are benign: they are small cysts or benign tumors (adenomas), but some are malignant (carcinomas). It is therefore very important to have a thyroid nodule examined by a doctor.
Not all neck swellings are thyroid nodules.
What causes thyroid nodules?
Several factors increase the likelihood of developing a thyroid nodule.
- Iodine deficiency
- An autoimmune thyroid disease
- Previous irradiation in the neck region
- Exposure to radioactive substances from, for example, a nuclear power plant (e.g. Chernobyl)
- Female sex, as girls are at a higher risk of developing a thyroid nodule
- Certain hereditary conditions.
How are thyroid nodules diagnosed?
Sometimes you can feel the nodule yourself, or your doctor may discover it during an exam. However, your doctor will usually need to order one or more of the following tests:
- Thyroid ultrasound: This test uses sound waves to determine whether a nodule is solid or a fluid-filled cyst, benign or malignant.
- Blood test: This test checks the levels of hormones secreted by the thyroid gland.
- Fine-needle biopsy of the thyroid gland: If, after the ultrasound, it is not completely clear what the lump is and if it is more than 1 cm in size, the lump will be punctured with a fine needle to take a sample of cells from one or more thyroid nodules. The samples are then sent to a laboratory.
- Thyroid scan: In this test, a small amount of radioactive iodine is given orally. The doctor will check to see how much of the radioactive iodine is absorbed by the nodules and how much is absorbed by normal thyroid tissue.
What are the signs and symptoms of thyroid nodules?
Most thyroid nodules do not produce any symptoms.
Although rare, nodules can press against other structures in the neck and cause symptoms, including:
- Difficulty swallowing or breathing
- Hoarseness or voice changes
- Pain in the neck
- Goitre (enlargement of the thyroid gland)
Hyperfunctioning thyroid nodules can lead to overproduction of thyroid hormones, also known as hyperthyroidism. Symptoms of hyperthyroidism include sweating, fast heart rate, weight loss, etc.
Thyroid nodules may also be associated with low thyroid hormone levels, or hypothyroidism.
How are thyroid nodules treated?
Treatment depends on the type of thyroid nodule. Treatment options include:
- No treatment/”watching and waiting” If the nodules are not cancerous, the ultrasound will be repeated every 6-12 months to monitor changes in the nodule.
- Surgery. If the biopsy tissue is malignant, the entire thyroid gland is often removed. If not all the cancer tissue can be removed and/or if the tumour has spread, there will usually be another treatment with radioactive iodine. It is best to discuss the details of this treatment with your treatment team.
After removal of the entire thyroid gland, the patient has to take thyroid hormone in tablet form for life.