Thyroid Gland Enlargement / Goiter
Goiter is an enlargement of your thyroid gland — a small, butterfly-shaped gland weighing less than an ounce, located just below your Adam's apple. Hormones produced by your thyroid gland regulate all aspects of your metabolism, from the rate at which your heart beats to the speed at which you burn calories.
Although generally not uncomfortable, goiter can interfere with swallowing or breathing. Goiters are more common in women and older adults.
The possible causes are numerous. In the past, the most common cause of goiter was a shortage of iodine in the diet in areas where the soil was deficient in iodine. Without enough dietary iodine, your thyroid can't make and release enough of the two essential iodine-containing hormones. Goiter became rare in the United States after iodized salt was introduced. In some parts of the world, however, goiter is still common because of iodine deficiency.
Treatment for goiter depends on the size of the enlargement, signs and symptoms, and the underlying cause.
Normally, your thyroid gland produces two main hormones — thyroxine and triiodothyronine (T-3). These hormones circulate in your bloodstream and help regulate your metabolism. They maintain the rate at which your body uses fats and carbohydrates, help control your body temperature, influence your heart rate and help regulate the production of proteins. Your thyroid gland also produces calcitonin — a hormone that regulates the amount of calcium in your blood.
Your pituitary gland and hypothalamus control the rate at which these hormones are produced and released. The process begins when the hypothalamus — an area at the base of your brain that acts as a thermostat for your whole system — signals your pituitary gland to make a hormone known as thyroid-stimulating hormone (TSH). Your pituitary gland — also located at the base of your brain — releases a certain amount of TSH, depending on how much thyroxine and T-3 are in your blood. Your thyroid gland, in turn, regulates its production of hormones based on the amount of TSH it receives from the pituitary gland.
Hormone level could be high, low or normal
Goiter doesn't necessarily mean your thyroid gland isn't producing hormones normally. Even when enlarged, your thyroid may produce below-normal, normal or above-normal amounts of hormones.
Enlargement of the gland can be uniform (diffuse goiter), or the gland may be enlarged due to one or more nodules (nodular goiter). Nodules are lumps within an otherwise normal thyroid gland.
One cause of goiter is iodine deficiency. In this situation, your thyroid can't make and release enough thyroxine and T-3 — both of which contain iodine — and it enlarges in response to excess stimulation from the pituitary.
Many causes of thyroid enlargement exist other than iodine deficiency. Some of the causes are serious, others not. Other causes of goiter include:
When to seek medical advice:
- Graves' disease. This disease, an autoimmune disorder, is the most common cause of an overactive thyroid (hyperthyroidism). In Graves' disease, antibodies produced by your immune system stimulate the thyroid to produce too much thyroxine. Normally, your immune system uses antibodies to help protect against viruses, bacteria and other foreign substances that invade the body. In Graves' disease, antibodies mistakenly attack your thyroid gland and occasionally the tissue behind your eyes and the skin of your lower legs. The overstimulation of your thyroid in Graves' disease results in uniform and nonpainful swelling of the gland.
- Hashimoto's disease. This disease, also called chronic lymphocytic thyroiditis, is a common cause of an underactive thyroid (hypothyroidism). Hashimoto's disease also is an autoimmune disorder and causes inflammation, which impairs your thyroid's ability to produce hormones. Then, your pituitary gland attempts to stimulate your thyroid gland to produce more thyroid hormones, causing your thyroid gland to enlarge.
- Multinodular goiter. In this condition, several nodules develop in both sides of your thyroid, resulting in overall enlargement of the gland. Multinodular goiter may occur with normal, low or excessive thyroid hormone production.
- Solitary thyroid nodules. A solitary nodule describes a single nodule that can occur in any part of your thyroid gland. Most nodules are noncancerous (benign) and don't lead to cancer.
- Thyroid cancer. Thyroid cancer is less common than benign thyroid nodules. Cancer of the thyroid often appears as an enlargement on one side of the thyroid.
- Pregnancy. A hormone produced during pregnancy, human chorionic gonadotropin (HCG), may cause slight uniform enlargement of your thyroid gland.
- Inflammation. Thyroiditis is an inflammatory condition of the thyroid. Various types of thyroiditis can result in an enlargement of your thyroid gland. Some may cause thyroid pain, often aggravated by swallowing or pressure. Some types of thyroiditis are associated with hyperthyroidism, while others are associated with hypothyroidism.
If you have had persistent widespread swelling of the front of your neck, above and between your collarbones, your thyroid gland may be enlarged. See your doctor, who can determine whether your thyroid is causing your neck to be swollen and what the reason might be.
Goiter symptoms may include:
- Enlargement of your thyroid gland, resulting in swelling of your neck
- A tight feeling in your throat
- Difficulty swallowing
- Difficulty breathing
|You may experience other signs and symptoms depending on the underlying cause of the goiter.
Goiter may cause your neck to appear swollen. By examining your neck, your doctor can determine the degree of gland enlargement and the areas of tenderness. In some cases, your doctor may be able to feel the presence of nodules.
Diagnosing goiter may also involve:
- A hormone test. Blood tests can determine the amount of hormones produced by your thyroid and pituitary glands. If your thyroid is underactive, the level of thyroid hormone will be low. At the same time, the level of thyroid-stimulating hormone (TSH) will be elevated because your pituitary gland tries to stimulate your thyroid gland to produce more thyroid hormone. Goiter associated with an overactive thyroid usually involves a high level of thyroid hormone in the blood and a lower than normal TSH level.
- An antibody test. Some causes of goiter involve production of abnormal antibodies. A blood test may confirm the presence of antibodies.
- Ultrasonography. A wand-like device (transducer) is held over your neck. Sound waves bounce through your neck and back, forming images on a computer screen. The images reveal the size of your thyroid gland and whether the gland contains nodules that your doctor may not have been able to feel.
- A thyroid scan. During a thyroid scan, you'll have a radioactive isotope injected into the vein on the inside of your elbow. You then lie on a table with your head stretched backward while a special camera produces an image of your thyroid on a computer screen. The time needed for the procedure may vary, depending on how long it takes the isotope to reach your thyroid gland. Thyroid scans generate information about the nature of the thyroid enlargement and the function of the gland.
Goiter treatment depends on the size of the enlargement, your signs and symptoms, and the underlying cause. Your doctor may recommend:
- Observation. If your goiter is small and doesn't cause you much of a problem, and your thyroid is functioning normally, your doctor may suggest a wait-and-see approach.
- Medications. If you have hypothyroidism, thyroid hormone replacement with levothyroxine (Levothroid, Synthroid) will resolve the symptoms of hypothyroidism as well as slow the release of thyroid-stimulating hormone from your pituitary gland, often decreasing the size of the goiter. For an inflammation of your thyroid gland, your doctor may suggest aspirin or a corticosteroid medication to treat the inflammation. For goiters associated with hyperthyroidism, you may need medications to normalize hormone levels.
- Surgery. Removing all or part of your thyroid gland (total or partial thyroidectomy) is an option if you have a large goiter that is uncomfortable or causes difficulty breathing or swallowing, or in some cases, if you have nodular goiter causing hyperthyroidism. Surgery is also the treatment for thyroid cancer. You may need to take levothyroxine after surgery, depending on the amount of thyroid removed.
- Radioactive iodine. In some cases, radioactive iodine is used to treat an overactive thyroid gland. The radioactive iodine is taken orally and reaches your thyroid gland through your bloodstream, destroying thyroid cells. The treatment results in diminished size of the goiter but eventually may also cause an underactive thyroid gland. Hormone replacement with the synthetic thyroid hormone levothyroxine then becomes necessary, usually for life.