(Simple Nontoxic Goiter; Euthyroid Goiter)
(See also Overview of the Thyroid Gland.)
Goiter is noncancerous enlargement of the thyroid gland.
Noncancerous thyroid enlargement can occur because of lack of iodine in the diet or ingestion of certain substances or drugs.
People often have no symptoms.
Doctors do blood tests to determine how well the thyroid is working.
Doctors may treat the cause of the enlargement, and sometimes people need surgery to remove part of the enlarged thyroid.
The most common cause of goiter in most of the world is
The thyroid gland uses iodine to make thyroid hormone. When there is not enough iodine, the thyroid gland grows larger in an attempt to compensate. However, in the United States, most salt is fortified with iodine, so lack of iodine is not a common cause of goiter.
Other causes of goiter include
Sometimes a goiter forms temporarily during puberty, pregnancy, or menopause.
The thyroid gland also can enlarge if it becomes inflamed (thyroiditis, such as Hashimoto thyroiditis) or if thyroid cancer develops. Thyroid enlargement due to inflammation or cancer is not considered a goiter.
Doctors usually do blood tests to determine how the gland is functioning (thyroid function tests). They measure blood levels of the thyroid hormones thyroxine (T4, or tetraiodothyronine) and triiodothyronine (T3) and thyroid-stimulating hormone (TSH). Sometimes doctors also look for antibodies that attack the thyroid gland (antithyroid antibodies) in the blood, which are a sign of thyroid inflammation.
Doctors do a radioactive iodine uptake test and a thyroid scan. For these tests, the person ingests (or is injected with) a small amount of radioactive iodine. The radioactive iodine concentrates in the thyroid gland. A scanner can detect how much iodine is taken up by the gland and a gamma camera (which detects radiation) produces a picture of the thyroid gland. These scans show any physical abnormalities in the gland that might suggest Graves disease, nodules, or thyroiditis.
Treatment depends on the size and cause of goiter.
In iodine-deficient areas, people are given iodine supplements. Iodine may be added to salt, water, or crops to eliminate iodine deficiency in the area. People should stop eating foods that inhibit thyroid hormone production.
When diet is not a cause, some people may be given thyroid hormone replacement with l-thyroxine. This drug blocks production of TSH and may shrink the goiter.
People with very large goiters may need surgery to remove part of the thyroid or may be given radioactive iodine to shrink the gland enough to prevent interference with breathing or swallowing or to correct cosmetic problems.