What causes thyroid nodules? 3 possible conditions
A thyroid nodule is a lump in your thyroid gland. It can be solid or filled with fluid. You can have a single nodule or a cluster of nodules. Thyroid nodules are common and rarely cancerous.
Your thyroid is a small butterfly-shaped gland that is located near your larynx (voice box). Your thyroid produces two hormones and secretes them into your bloodstream. The two thyroid hormones affect your heart rate, body temperature, and many body processes—a group of chemical reactions that, together, are called “metabolism.”
Thyroid nodules are classified cold, warm, or hot, depending on whether they produce thyroid hormones or not. Cold nodules don’t produce thyroid hormones. Warm nodules act as normal thyroid cells. Hot nodules overproduce thyroid hormones.
Most thyroid nodules are not serious and don’t cause any symptoms. It’s possible for you to have a thyroid nodule without knowing it. Unless it becomes large enough to press against your windpipe and hamper your breathing, you may have no symptoms. Your doctor may be able to feel it during a physical exam.
According to the American Thyroid Association, about 90 percent of all thyroid nodules are benign—in other words, noncancerous (ATA, 2012).
The majority of thyroid nodules are an overgrowth of normal thyroid tissue. What causes the overgrowth of tissue is not known.
Nodules are often found in people who have Hashimoto’s disease, an autoimmune disease that leads to hypothyroidism. Individuals who have thyroiditis (chronic inflammation of the thyroid) are also prone to developing thyroid nodules. If you have a diet low in iodine, you may develop thyroid nodules. This isn’t as common in the United States as it is in other countries because of the wide use of iodized salt and iodine-containing multivitamins.
People who had X-rays performed on their thyroid in infancy or childhood are more likely to develop thyroid nodules (Johns Hopkins). Having a preexisting thyroid condition or a family history of thyroid nodules can increase your chances of having nodules. Thyroid nodules are more common in women; in men, nodules are more likely to be cancerous.
The likelihood of developing a thyroid nodule increases with age. According to the American Thyroid Association, about one-half of people aged 60 years old and older develop nodules (ATA, 2012).
You may have a thyroid nodule and not have any noticeable symptoms. If the nodule increases in size, you may notice:
- enlarged thyroid (goiter)
- breathing difficulties, if the nodule is pressing against your windpipe
- hoarse voice
- pain at the base of the neck
- swallowing difficulties
If your nodule is producing extra thyroid hormones, you may develop symptoms of hyperthyroidism. These include:
- rapid, irregular heartbeat
- unexplained weight loss
- muscle weakness
- difficulty sleeping
If your nodule is associated with Hashimoto’s disease, you will have symptoms of hypothyroidism. These include:
- constant fatigue
- sensitivity to cold
- dry skin and hair
- brittle nails
- unexplained weight gain
You may not know you have a nodule until your doctor finds it during a general physical exam. He or she may be able to feel the nodule. Your doctor will probably refer you to an endocrinologist—a physician who specializes in all aspects of the endocrine system, including the thyroid. The endocrinologist will be interested in whether you have a family history of thyroid nodules and whether you underwent radiation treatment of the head or neck as an infant or child.
Your endocrinologist will use one or more of the following tests to diagnose and assess your nodule:
- fine needle aspiration, to evaluate your nodule and rule out cancer
- thyroid scan, which uses radioactive iodine to assess your nodule as hot, warm, or cold
- thyroid ultrasound, which provides image of your nodule
- blood tests, to check your levels of the thyroid hormones and thyroid stimulating hormone (TSH)
Your treatment options will depend on the type of thyroid nodule you have. If your nodule isn’t cancerous and isn’t causing problems, your endocrinologist may decide that it doesn’t need treatment at all. Instead, he or she will closely monitor the nodule with regular office visits and thyroid ultrasounds.
If your nodule is overproducing thyroid hormones, your endocrinologist will probably use radioactive iodine or surgery to eliminate the nodule. If you were experiencing symptoms of hyperthyroidism, this should resolve your symptoms. If too much of your thyroid is destroyed/removed, you may need to take synthetic thyroid hormones for the rest of your life.
Alternatively, your endocrinologist may try giving you synthetic thyroid hormone. Your pituitary gland will detect the extra thyroid hormone and signal your thyroid to lower production.
Nodules that are fluid-filled will be drained during a fine-needle aspiration.
Nodules that start as benign rarely turn cancerous. However, your endocrinologist will likely perform biopsies occasionally to rule out the possibility.
There is no way to prevent the development of a thyroid nodule. Once you are diagnosed, your endocrinologist will check your condition through regular blood testing and annual ultrasounds. Treatment measures are used for hot or warm nodules that affect thyroid hormone production. However, the majority of noncancerous nodules aren’t harmful, and many don’t need treatment.
- Thyroid nodule. (2010, April 19). National Library of Medicine – National Institutes of Health. Retrieved July 19, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/007265.htm
- Thyroid nodules. (2012). American Thyroid Association. Retrieved July 19, 2012, from http://www.thyroid.org/patients/brochures/Nodules_brochure.pdf
- Thyroid nodules. (n.d.). Cleveland Clinic Diseases & Conditions. Retrieved July 29, 2012, from http://my.clevelandclinic.org/disorders/thyroid_nodule/hic_thyroid_nodules.aspx
- Thyroid nodules. (n.d.). Johns Hopkins Symptoms and Remedies. Retrieved July 29, 2012, from http://hopkins.portfolio.crushlovely.com/reference/article/thyroid-nodules
- Thyroid nodules. (2011, February 22). Mayo Clinic. Retrieved July 19, 2012, from http://www.mayoclinic.com/health/thyroid-nodules/DS00491
See a list of possible causes in order from the most common to the least.
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