Thyroid nodules are lumps that form inside the thyroid gland. They may be filled with fluid or thyroid tissue. They are quite common and most people who have them don't notice it, until their doctor discovers it during a routine examination.
What is the thyroid gland?
The thyroid gland is found in the lower front of the neck. It produces thyroid hormones, which are secreted into the blood and then carried throughout the body. Thyroid hormone is important because it helps the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.
What causes thyroid nodules?
There are several conditions that can cause nodules to develop in your thyroid gland. Here are a few examples:
|Thyroid cyst||A thyroid cyst in a lump that is usually filled with fluid. Sometimes solid components may be mixed with fluid in thyroid cysts.|
|Iodine deficiency||A lack of iodine in your diet can sometimes cause your thyroid gland to develop thyroid nodules. But iodine deficiency is uncommon in New Zealand where iodine is routinely added to table salt and other foods.|
|Thyroid adenoma||This is an overgrowth of normal thyroid tissue. It is unclear why this happens.|
|Ongoing inflammation of the thyroid (thyroiditis)||A thyroid disorder called Hashimoto's disease, can cause inflammation of the thyroid which results in enlargement of thyroid nodules. This often is associated with hypothyroidism (reduced activity of the thyroid gland).|
|Thyroid cancer||Cancerous thyroid nodules are rare (occur in less than 5 in every 100 people with thyroid nodules). You are at higher risk of thyroid cancer if you:
What are the symptoms of thyroid nodules?
Most thyroid nodules cause no symptoms at all. It is usually noticed when a person feels a lump in their throat or sees it the mirror. Sometimes your doctor may notice the swelling during a routine examination.
In rare cases thyroid nodules may cause pain. Sometime, if the nodule is large enough and positioned near the oesophagus (which lies behind the thyroid gland), it affects swallowing.
How is a thyroid nodule assessed?
Once a thyroid nodule is discovered, your doctor will try to determine whether the rest of your thyroid is healthy or whether the entire thyroid gland has been affected by a more general condition such as hyperthyroidism or hypothyroidism.
Your doctor will ask you questions about your symptoms and will feel your thyroid to see whether the entire gland is enlarged and whether a single or many nodules are present.
To assess the functioning of your thyroid gland, your doctor will also request blood tests to measure thyroid hormone levels. This is called a thyroid function test.
Sometimes your doctor may order more specialised tests such as:
- Ultrasound scan - this test can help your doctor decide if the thyroid nodule is filled with fluid or thyroid tissue, and it can also measure the size of the nodule. An ultrasound is a painless test.
- Thyroid scan (nuclear medicine scan) - during this test, radioactive iodine is injected into a vein in your arm. You lie on a table while a special camera produces an image of your thyroid on a computer screen.
- Fine needle biopsy - this involves removing small samples of tissue from the thyroid nodule with a thin needle. To reduce the discomfort from the needle, your doctor will use a local anaesthetic. The tissue samples are examined under a microscope for any unusual cells that may indicate cancer.
How is a thyroid nodule treated?
The treatment of a thyroid nodule depends mainly on the findings of the diagnostic tests and the type of nodule.
- If the thyroid nodule is not cancerous (benign), the nodule may be left as is and watched closely to make sure it does not grow any larger, or it may be surgically removed.
- If the thyroid nodule is cancerous, or highly suspicious of cancer, the nodule will be removed surgically. Most thyroid cancers can be cured and hardly ever cause life-threatening problems.
The following links provide further information on thyroid nodules. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.