The thyroid gland is a butterfly-shaped organ found in the center of the neck, below the Adam's apple. It creates and stores hormones that control the body's heart rate, blood pressure, and metabolism (how the body makes energy from food). Thyroid nodules are lumps or growths on the thyroid gland. They are fairly common, especially among people over 50. In most cases, these growths are benign (non-cancerous), but about five percent of thyroid nodules may be malignant, or cancerous.
Most thyroid nodules cause no symptoms, and are found by a doctor during a routine examination, or a medical test – such as a CT scan or ultrasound – ordered for another condition.
Some thyroid nodules can cause your thyroid gland to overproduce hormones, and cause hyperthyroidism. This can lead to symptoms such as:
- Restlessness or anxiety
- Increased appetite
- Rapid heart beat, or palpitations (a feeling of the heart "flopping" in the chest)
Large thyroid nodules can eventually press on the esophagus (swallowing tube) or the windpipe, and cause difficulty while swallowing or breathing.
The cause of most thyroid nodules is unknown. Some things that can increase your risk of developing thyroid nodules include:
- Low iodine in the diet. The thyroid gland uses iodine to produce its hormones.
- A family history of thyroid nodules
- Thyroid disease, such as Hashimoto's thyroiditis, which causes long-term inflammation of the thyroid gland
Many thyroid nodules are found by a doctor during a routine physical exam. Small nodules may be found during a CT scan or ultrasound ordered for another condition.
If your doctor suspects that you may have thyroid nodules, he or she may recommend one or more of the following tests:
- Ultrasound, which uses sound waves to make images of the thyroid gland
- A thyroid scan, which is an image taken of the thyroid gland after you have swallowed a small amount of radioactive iodine. Because the thyroid naturally uses iodine to produce some of its hormones, it absorbs the radioactive substance and allows the image to be made. The image will show if nodules are present on the thyroid gland.
Only a small percentage of nodules are turn out to be malignant (cancerous). In order to tell if the thyroid nodule is benign (non-cancerous) or malignant, your doctor may recommend one or more of the following tests:
- A TSH blood test. In an effort to get the thyroid working properly, the pituitary gland produces high levels of TSH, a hormone that usually stimulates the thyroid. Abnormal levels of TSH in the blood can indicate that a thyroid nodule may be benign.
- A fine-needle aspiration biopsy. The doctor uses a thin, small needle to remove a sample of cells from the nodule. The sample is then sent to a lab for analysis. The procedure takes about 20 minutes, and is almost completely accurate in diagnosing a malignancy.
- Most nodules are harmless and require no treatment. If you have a benign (non-cancerous) nodule, your doctor will want to check its size every six months to make sure it doesn't grow larger.
- A doctor may prescribe anti-thyroid drugs to lower the production of thyroid hormones in a nodule that causes hyperthyroidism.
- A doctor may use radioactive iodine to destroy part or all of the thyroid gland, and make it unable to produce thyroid hormones. The patient will need to take replacement thyroid hormones for the rest of his or her life.
- A doctor uses alcohol ablation to inject alcohol into a nodule. This can shrink the nodule, and improve any symptoms of hyperthyroidism.
- If a benign nodule has grown so large that a patient has trouble breathing or swallowing, a doctor will recommend surgery to remove the nodule and most of the thyroid gland. This is called near-total thyroidectomy. The patient will need to take replacement thyroid hormones for the rest of his or her life.
- If a fine needle biopsy shows that a thyroid nodule is cancerous, your doctor will also recommend a near-total thyroidectomy.
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