Hashimoto thyroiditis is chronic, autoimmune inflammation of the thyroid gland.
Hashimoto thyroiditis results when antibodies in the body attack the cells of the thyroid gland—an autoimmune reaction.
At first, the thyroid gland may function normally, be underactive (hypothyroidism) or, rarely, overactive (hyperthyroidism)
Most people eventually develop hypothyroidism.
People with hypothyroidism usually feel tired and cannot tolerate cold.
The diagnosis is based on results of a physical examination and blood tests.
People with hypothyroidism need to take thyroid hormone for the rest of their life.
(See also Overview of the Thyroid Gland.)
Thyroiditis refers to any inflammation of the thyroid gland. Inflammation of the thyroid may be caused by a viral infection or an autoimmune disorder.
Hashimoto thyroiditis is the most common type of thyroiditis and the most common cause of hypothyroidism. For unknown reasons, the body turns against itself (an autoimmune reaction). The thyroid is invaded by white blood cells, and antibodies are created that attack the thyroid gland (antithyroid antibodies).
In about 50% of people with Hashimoto thyroiditis, the thyroid is underactive initially. In most of the rest, the thyroid is normal at first (although in a small number of people, the gland initially becomes overactive), after which it usually becomes underactive.
Some people with Hashimoto thyroiditis have other endocrine disorders, such as diabetes, an underactive adrenal gland, or underactive parathyroid glands, and other autoimmune disorders, such as pernicious anemia, rheumatoid arthritis, Sjögren syndrome, or systemic lupus erythematosus (lupus).
Hashimoto thyroiditis is most common among women, particularly older women, and tends to run in families. The condition occurs more frequently among people with certain chromosomal abnormalities, including Down syndrome, Turner syndrome, and Klinefelter syndrome.
Symptoms of Hashimoto Thyroiditis
Hashimoto thyroiditis often begins with a painless, firm enlargement of the thyroid gland or a feeling of fullness in the neck. The gland usually has a rubbery texture and sometimes feels lumpy. If the thyroid is underactive, people may feel tired and intolerant of cold and have other symptoms of hypothyroidism. The few people who have an overactive thyroid (hyperthyroidism) initially may be aware of their heartbeats (palpitations) or have nervousness and intolerance of heat.
Diagnosis of Hashimoto Thyroiditis
Thyroid function blood tests (measurement of thyroid-stimulating hormone and thyroxine and also measurement of triiodothyronine if hyperthyroidism is suspected)
Thyroid antibodies
Sometimes a thyroid ultrasound
Doctors do an examination of the thyroid gland. They feel the person's neck to see whether the thyroid gland is enlarged, is tender, or contains lumps (nodules).
An ultrasound of the thyroid may be done if the thyroid feels like it has bump (nodules).
Doctors measure blood levels of the thyroid hormone thyroxine (T4) ) and thyroid-stimulating hormone (TSH, a hormone produced by the pituitary gland to stimulate the thyroid gland to produce thyroid hormones) to determine how the gland is functioning (thyroid function blood tests). If doctors suspect the person has hyperthyroidism, they measure the level of the hormone triiodothyronine (T3) in the blood. They also do a blood test for antibodies that can attack the thyroid gland.
Treatment of Hashimoto Thyroiditis
Usually thyroid hormone replacement when the person has symptoms of hypothyroidism and the TSH level is elevated in the blood
Avoidance of excess iodine in food or nutritional supplements
Most people eventually develop hypothyroidism and then must take thyroid hormone replacement therapy for the rest of their life. Thyroid hormone may also be useful in reducing the size of the enlarged thyroid gland.
People with Hashimoto thyroiditis who are not taking thyroid hormone replacement should avoid high doses of iodine (which can cause hypothyroidism) from natural sources, such as kelp tablets and seaweed; however, iodized salt and iodine-fortified bread are allowed because they contain lower amounts of iodine.
