What is the thyroid gland?
The thyroid gland sits at the front of the neck, just below the “Adam’s apple”. It produces two thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine), which regulate how the body uses and stores energy — what we simply call “our metabolism”.
What are nodules and who is at risk of developing them?
A thyroid nodule is a growth of thyroid tissue or a cystic (fluid-filled) lump. Nodules are common, and the chance of developing them increases with age. You can have a nodule without knowing it; you may notice it if it starts to grow, especially if the swelling can be seen from the outside. Although nodules usually cause no symptoms, a fairly large one can sometimes cause pain or hoarseness, or make swallowing or breathing difficult.
Doctors pay attention to thyroid nodules because they can sometimes conceal a cancer. About 8% of nodules in men and 4% in women are malignant. By contrast, about 90–95% of all nodules are benign.
The cause of benign nodules is usually unknown, but they often occur in members of the same family. Worldwide, a lack of iodine in the diet is a very common cause.
How are they diagnosed?
Most nodules are found during an ordinary clinical examination. Once a nodule has been found, your doctor will ask for the appropriate tests to find out whether your thyroid is working normally or is overactive.
These tests are not enough to rule out cancer. To find out more about the nodule (or nodules), one or more of the following tests may be done:
Thyroid ultrasound. This gives a complete picture of the gland and shows whether the nodule is solid or filled with fluid (cystic). Based on the nodule’s appearance on the scan (its ultrasound features), ultrasound can judge with up to 75% reliability whether the nodule is benign or not:
| Ultrasound finding | Assessment |
|---|---|
| Well-defined margins | Benign feature |
| Thin hypoechoic halo | Benign feature |
| Condensed colloid | Benign feature |
| Hypoechoic and solid | Sometimes suspicious |
| Microcalcifications | Suspicious for malignancy |
Thyroid elastography. This checks how stiff (hard) the nodule is and picks out suspicious nodules with a high degree of reliability. It is especially useful when there are many nodules and a choice has to be made about which ones to sample with a needle.
Fine-needle aspiration biopsy (FNA). A fine needle is used to take cells or fluid from the nodule. This test can accurately identify malignant or suspicious nodules. Ultrasound is used to guide the biopsy, especially with very small nodules.
Thyroid scan (scintigraphy). Using a small amount of radioactive iodine, this shows whether the nodule is producing hormones. It is usually done when an overactive (“hot”) nodule is suspected.
How are they treated?
Treatment depends on the type of nodule. Surgical removal of the thyroid is recommended for nodules that are suspicious, or when cancer has been confirmed. After the operation, radioactive iodine treatment may be given to destroy any remaining thyroid cells.
Benign nodules may need to be removed when their size causes problems with swallowing or breathing. Overactive nodules are almost never malignant, but they can cause hyperthyroidism; they are treated with surgery or with radioactive iodine.
Any nodule that is not removed should be monitored every 6 to 12 months, with a clinical examination, an ultrasound scan or both. If the nodule grows, a second FNA biopsy may be needed. Even if the biopsy shows that it is benign, surgical removal may be needed if it keeps growing.
What does this mean for you?
If you think you may have thyroid nodules, see an endocrinologist for a diagnosis and the right treatment. If you do have nodules, make sure you follow your doctor’s instructions for monitoring them.
Practising endocrinology since 1997 at her clinic in Chalandri, Athens. About the doctor
This article is for information only and does not replace a medical examination. For any health concern, please consult your doctor.