The term thyroid nodule refers to an abnormal growth of thyroid gland cells that form a lump within the thyroid gland. A thyroid nodule can be noncancerous (benign) or cancerous (malignant) and may be filled with fluid or thyroid gland cells. Thyroid nodules occur more frequently in women than in men. The risk of developing thyroid nodules may increase as we age.
Although, only a few thyroid nodules are cancerous, certain risk factors such as a hard nodule, age older than 70 and younger than 20, hoarse voice, history of head or neck radiation exposure, being male, and family history of thyroid cancer(medullary thyroid cancer), and multiple endocrine neoplasia type II, may increase the chance for developing cancerous thyroid nodules.
The cause of most thyroid nodules is not known, but lack of iodine can cause thyroid nodules. Chronic inflammation of the thyroid (Hashimoto’s disease) that results in reduced thyroid gland activity may also cause thyroid nodules.
Thyroid nodules do not cause any symptoms in most cases. However, if the nodule is very large, it can compress other structures in the neck and cause pain, difficulty in swallowing or breathing, hoarseness or change in voice, and goiter (enlargement of thyroid gland). If the cells in the nodule produce thyroid hormones, the nodule may produce symptoms of hyperthyroidism such as sudden, unexplained weight loss, nervousness, muscle weakness, increased appetite, trouble sleeping, and rapid or irregular heartbeat. Sometimes, thyroid nodules occur in patients with Hashimoto’s disease, causing dry skin, hair loss, swelling in the face, intolerance to cold, fatigue, and unintentional weight gain.
Since most patients with thyroid nodules do not have symptoms, most nodules are discovered by the doctor during a routine physical examination of the neck or imaging tests. Once a nodule is discovered, the following tests may be done:
- Fine-needle aspiration (FNA) biopsy : Your doctor will use a very thin needle to withdraw cells from the thyroid nodule which are examined under a microscope. This test helps to distinguish between non cancerous and cancerous thyroid nodules.
- Thyroid scan : A thyroid scan is a nuclear medicine test that allows your doctor to check how well the thyroid gland is functioning. It uses a radioactive tracer and a scanner to measure how much tracer the thyroid gland absorbs from the blood.
- Ultrasound of the thyroid : It uses sound waves to create images of your body. This test uses a lubricating gel and a transducer rubbed over the neck to look at the size and texture of the thyroid gland. This test can tell whether a nodule is a fluid-filled cyst, or a solid mass of tissue.
- Thyroid stimulating hormone Test (TSH test) : This test measures blood levels of the thyroid-stimulating hormone (TSH), which is released by your pituitary gland. This test helps to determine whether your thyroid gland is functioning normally.
Treatment depends on the type of thyroid nodule. If a thyroid nodule is not cancerous, careful follow-up is the only recommended treatment. This follow- up may involve a repeated thyroid biopsy and an ultrasound after the diagnosis.
Sometimes, levothyroxine (thyroid hormone) drug may be prescribed to suppress the production of the thyroid hormone if the nodule is non cancerous. Your doctor may use radioactive iodine to reduce the size and activity of the nodule in patients with overactive nodules. This treatment should not be given for pregnant women and women being treated with radioactive iodine should avoid pregnancy.
You will need to have surgery to remove part or all of your thyroid gland if your nodule is cancerous or suspected to be cancerous or causes problems with swallowing or breathing.