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 is a lump that's 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 Aotearoa New Zealand where iodine is routinely added to table salt and other foods.
• Thyroid adenoma: This is an overgrowth of normal thyroid tissue. It's not clear 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 is often associated with hypothyroidism (reduced activity of the thyroid gland). 
• Thyroid cancer: Cancerous thyroid nodules are rare – they occur in fewer than 5 in every 100 people with thyroid nodules. You are at higher risk of thyroid cancer if you:
  • have a family history of thyroid or other endocrine cancers
  • are younger than 30 years or older than 60 years of age
  • have a history of radiation exposure, particularly to the head and neck.

Most thyroid nodules cause no symptoms at all. They're usually found when a person feels a lump in their throat or sees it in the mirror. Sometimes your healthcare provider may notice the swelling during a routine examination.

In rare cases, thyroid nodules may cause pain in your neck, jaw or ear. Sometimes, if the nodule is large enough and positioned near the oesophagus (which lies behind the thyroid gland), it affects swallowing.

Once a thyroid nodule is discovered, your healthcare provider 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 healthcare provider 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 check how your thyroid gland is working, your healthcare provider will also request blood tests to measure thyroid hormone levels. This is called a thyroid function test.

Sometimes your healthcare provider may order more specialised tests such as:

• Ultrasound scan – this test can help your healthcare provider 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. Read more about nuclear medicine thyroid scans(external link).
• 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, a local anaesthetic will be used. The tissue samples are examined under a microscope for any unusual cells that may indicate cancer.

The treatment of thyroid nodules depends mainly on the findings of the diagnostic tests and the type of nodule.

• If the thyroid nodule is not cancerous, the nodule may be left as it is (and watched closely to make sure it doesn't 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.

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