A goiter is not a specific disease, but is a term used to describe an enlarged thyroid gland. The thyroid gland is a small butterfly-shaped gland located at the base of the front of the neck. It secretes hormones that help in the regulation of a number of functions in the body including heart rate, body temperature, and metabolism.
Are all goiters the same? Goiters can be very different, both in terms of their cause as well as their seriousness. They can be so small as to only be detected during physical examination or large enough to be seen protruding from the lower neck. They can develop for no apparent reason, or be associated with other diseases. They can lead to an overproduction or an underproduction of thyroid hormones or be present in someone with normal thyroid function. Some of the reasons for enlargement of the thyroid gland are:
- Simple goiter. These can occur without a known cause. They can also develop when the thyroid gland is unable to make enough thyroid hormone to meet the body’s needs. One reason for this is a diet deficient in iodine, since iodine is necessary for the production of thyroid hormones. Without an adequate supply of iodine, the thyroid becomes larger in order to increase its production of thyroid hormone. The addition of iodine to salt in the 1920’s has markedly reduced the occurrence of this type of goiter in the U.S.
- Multinodular goiter is associated with several small growths called nodules that develop inside the thyroid gland. In many cases, one or more of these nodules will produce an excess of thyroid hormone.
- Graves’ disease is an autoimmune disease in which antibodies produced by the immune system mistakenly attack the thyroid gland. This results in swelling of the thyroid gland and an overproduction of thyroid hormone (hyperthyroidism).
- Hashimoto’s disease. This is another autoimmune disease that causes inflammation and swelling of the thyroid gland. Hashimoto’s disease is typically associated with an underproduction of thyroid hormone (hypothyroidism).
- Thyroid cancer is the most serious reason for enlargement of the thyroid gland. Typically this will appear as an enlargement of only one side (lobe) of the thyroid gland.
What are the symptoms of goiter? Symptoms associated with a goiter can be due to the physical size of the goiter or due to the effects of too high or too low levels of thyroid hormone. Visually, a goiter may appear as a swelling in the front of the neck. As the goiter gets larger, it can compress the trachea (windpipe) and esophagus (swallowing tube). This can cause a tight feeling in the throat, coughing, difficulty swallowing, hoarseness, and shortness of breath. Symptoms of thyroid hormone deficiency (hypothyroidism) include fatigue, constipation, dry skin, weight gain and menstrual irregularities. Symptoms of excess thyroid hormone production (hyperthyroidism) include rapid heartbeat, diarrhea, shaking, sweating, and heat intolerance.
How are goiters diagnosed? Once a goiter is discovered, the next step in its evaluation is to determine what is responsible for the thyroid enlargement. This can require several types of tests, since there are a number of reasons why the thyroid could be enlarged. Blood tests for thyroid function testing can tell the doctor if the thyroid is over-producing or under-producing thyroid hormone. Antibody tests look for evidence of an autoimmune disorder. Imaging tests including ultrasound and a radioactive scan of the thyroid can provide information about the size and possible presence of nodules. A CT or MRI scan may be needed to assess the size and nature of any nodules or masses. A fine-needle aspiration may be used to further evaluate a nodule or mass suspected of being cancer.
How is goiter treated? Treatment of the goiter depends primarily on the underlying cause for the thyroid enlargement. In situations in which there is no apparent cause for the goiter, the thyroid functions are normal, and the patient has no symptoms due to the goiter, the best approach is usually to monitor the thyroid enlargement periodically without treating. Other ways to manage a goiter include:
- Medications. If iodine deficiency is the cause for the goiter, using iodinized salt will lead to shrinking of the thyroid. Thyroid hormone replacement pills (Levothroid®, Synthroid®), can reduce the size of the goiter if it is due to underactive thyroid production. For goiters associated with an excess of thyroid hormone, anti-thyroid medications (eg, PTU, methimazole) or medications to reduce hyperthyroid symptoms (e.g. beta blockers) may be used while awaiting a more permanent treatment.
- Radioactive iodine destroys thyroid cells and is used primarily for goiters that are producing an excessive amount of thyroid hormone. Multinodular goiters or a goiter associated with Graves’ disease could fall into this category. This treatment is effective in reducing the size of the goiter, but may also destroy so much of the thyroid that thyroid replacement becomes necessary.
- Surgery. This treatment is typically used only with large goiters that are causing symptoms due to compression of the trachea or esophagus, or when the goiter is due to cancer.
From this discussion, it is obvious that there are a number of possible causes for goiters and there is no “one size fits all” treatment. Since goiters can range from being totally benign to life-threatening, it is important that the specific underlying cause is determined so that the most appropriate treatment (if treatment is necessary) can be provided.