What is thyroid nodule?
A thyroid nodule is defined as an abnormal or unusual growth of thyroid cells that occurs in the form of a lump in your thyroid gland. A thyroid nodule can be solid or fluid-filled and noncancerous (benign) or cancerous (malignant) in nature. They are relatively common with more than 90 percent of the thyroid nodules being noncancerous. They occur more frequently in women than in men and the risk of developing these may increase as we age.
The thyroid gland is a butterfly-shaped gland located in front of your neck just below the voice box (larynx). It secretes hormones that help regulate your body’s metabolism such as heart rate, breathing, body temperature, weight, nervous system, blood pressure, and several other body functions.
Causes of thyroid nodule
The cause of most thyroid nodules is unknown, however, some of the conditions that can trigger the development of nodules in your thyroid gland include:
- Overgrowth of thyroid tissue
- Inflammation of the thyroid
- Multinodular goitre
- Thyroid cyst
- Iodine deficiency
- Thyroid cancer
- Hashimoto’s disease
Symptoms of thyroid nodules
Thyroid nodules generally do not cause any symptoms; however, if the nodules enlarge in size, it can compress other structures in the neck leading to:
- Pain at the base of the neck
- Breathing difficulties
- Swallowing difficulties
- Hoarse voice
- Goitre (enlarged thyroid gland)
- Cough, unrelated to cold
If the cells in the nodule produce excess thyroid hormones, you may exhibit symptoms of hyperthyroidism such as:
- Sudden and unexplained weight loss
- Muscle weakness
- Increased appetite
- Trouble sleeping
- Rapid or irregular heartbeat
Risk factors for thyroid nodule
Some of the risk factors for developing thyroid nodules include:
- Gender: Females are 2 to 3 times more likely than men to develop thyroid nodules.
- Family history: Your chances of developing thyroid nodules are increased if your parents or siblings have had thyroid nodules or other thyroid conditions.
- Advanced age: The likelihood of developing thyroid nodules is higher as you get older.
- Exposure to radiation: History of exposure to radiation from medical treatments can trigger development of thyroid nodules.
- If you have a pre-existing thyroid disorder such as thyroiditis, your risk is higher.
Diagnosis of thyroid nodule
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:
- Thyroid function 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 and whether you have hypothyroidism or hyperthyroidism.
- Ultrasound of the thyroid: This test uses sound waves to create images of your thyroid. The test utilises a lubricating gel and a device called a transducer to gently move over your 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.
- Fine-needle aspiration (FNA) biopsy: Your doctor will use a very thin needle to withdraw cells from the thyroid nodules which are examined under a microscope. This test helps to distinguish between noncancerous and cancerous thyroid nodules.
- Thyroid scan: A lab technician introduces a tiny quantity of radioactive iodine into your bloodstream with a syringe and a special camera captures images of the thyroid gland to view nodules and allows your doctor to check how well the thyroid gland is functioning.
Treatment for thyroid nodules
Treatment depends on the size and the type of the thyroid nodule and may involve the following methods:
- Watchful waiting: If a thyroid nodule is not cancerous, careful follow-up is the only recommended treatment. This involves regular physical exams and thyroid function tests. You may also have a thyroid biopsy and ultrasound exam to look for any change in nodules.
- Surgery: 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 compressing other structures in the neck causing “obstructive symptoms“ such as difficulty breathing or swallowing.
- Radioactive iodine: This is used when patient is not a good candidate for surgery. Your doctor may use radioactive iodine treatment to reduce the size and activity of the nodule in patients with overactive nodules and goitres with many nodules. In this method, a tiny amount of radioactive iodine is taken by mouth which is absorbed by the thyroid gland. The radioactive iodine causes the nodules to shrink. This treatment should not be given to pregnant women and women trying to conceive.