The thyroid is a butterfly-shaped endocrine gland in the neck made up of two lobes that are connected with a strip of tissue called the thyroid isthmus. The thyroid’s job is to release certain hormones into the bloodstream, such as triiodothyronine (T3), tetraiodothyronine (thyroxine, or T4), and calcitonin, to help regulate the body’s metabolism, growth, and maturation. Sometimes, large bumps or lumps called thyroid nodules grow on the gland. The vast majority of these nodules are benign (non-cancerous), but about 5 percent of them are cancerous, according to the American Cancer Society. Thyroid nodules are more common in women than in men. They also most-commonly develop in older adults, according to the National Institutes of Health.
Types and Causes of Thyroid Nodules
Thyroid nodules result from the abnormal growth of cells. These thyroid growths may be:
A single nodule, or multiple small nodules grouped togetherFilled with fluid or colloid (a stored form of thyroid hormone)Solid or hard — these nodules are more likely to be cancerousProducing thyroid hormones
It’s unknown what causes most thyroid nodules, according to the American Thyroid Association. Known causes include Hashimoto’s thyroiditis, a condition in which the immune system attacks thyroid tissue, as well as iodine deficiency, which is uncommon in the United States.
Thyroid Nodule Symptoms
Most of the time, thyroid nodules do not cause any symptoms. Many people are unaware that they have them. A large nodule, however, can cause a noticeable swelling in the neck. The nodule may also press against structures in the neck, resulting in:
Throat painHoarsenessDifficulty breathing, particularly when lying downDifficulty swallowing
Nodules that produce thyroid hormones can cause hyperthyroidism (overactive thyroid gland), which may lead to various symptoms, including:
Nervousness, restlessness, irritabilityFast heartbeat (pulse)Profuse sweating or intolerance to heatWeight lossIncreased appetiteIrregular menstruationSkin flushingTremor
Hashimoto’s disease is a common cause of hypothyroidism, or underactive thyroid gland. People with thyroid nodules from the disease may also experience various symptoms of hypothyroidism, such as fatigue, depressed mood, hair loss, chills, and weight gain.
Thyroid Nodule Diagnosis
Doctors typically find possible thyroid nodules during routine physical exams or from imaging tests for other health conditions. After finding a potential nodule, your doctor may conduct one or more tests, including:
Blood tests that measure your levels of T4, thyroid-stimulating hormone (TSH), or other thyroid hormones to see if your gland is functioning properlyThyroid ultrasound, which uses high-frequency sound waves to image the thyroid gland, determine the location and size of any nodules, and detect if the nodules are fluid-filled or solidThyroid scan, which uses radioactive iodine to help determine if nodules are benign or cancerousThyroid fine-needle aspiration biopsy, in which multiple thyroid tissue samples are removed using a thin needle and then examined under a microscope
Thyroid Nodule Treatment
There are several different treatments for thyroid nodules that your doctor may use, depending on the type of nodule you have and your specific health situation. If your thyroid nodule is benign (again, most are benign), your doctor may advise “watchful waiting,” or simply monitoring your thyroid during regular check-ups for any changes. Your doctor may surgically remove your thyroid if your nodule is:
CancerousSuspicious (potentially cancerous)Causing serious symptoms, such as disrupting breathing or swallowingCausing hyperthyroidism
If you have a benign thyroid nodule that isn’t overproducing hormones, your doctor may try to shrink it by using thyroid hormone suppression therapy. This treatment uses medications that cause the pituitary gland to produce less TSH, which is responsible for thyroid tissue growth. If your nodule is producing too much of certain thyroid hormones, your doctor may treat it with radioactive iodine, which reduces the size and activity of the nodule.
