Thyroiditis
Thyroiditis is inflammation of the thyroid gland.
The three types of thyroiditis are Hashimoto's thyroiditis (autoimmune thyroiditis), subacute painful thyroiditis (granulomatous thyroiditis), and subacute painless thyroiditis (silent lymphocytic thyroiditis, postpartum thyroiditis).
Hashimoto's Thyroiditis: Hashimoto's 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 (see Section 16, Chapter 186)); the thyroid is invaded by white blood cells, and antibodies are created that attack the thyroid gland. Many people with Hashimoto's thyroiditis have other endocrine disorders, such as diabetes, an underactive adrenal gland, or underactive parathyroid glands, and other autoimmune diseases, such as pernicious anemia, rheumatoid arthritis, Sjögren's syndrome, or systemic lupus erythematosus (lupus).
Hashimoto's 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, Turner's, and Klinefelter's syndromes.
Hashimoto's 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. In about 50% of people with Hashimoto's thyroiditis, the thyroid becomes underactive. In most of the rest, the thyroid remains normal. In a small number of people, the gland initially becomes overactive, after which it usually becomes underactive.
Doctors perform thyroid function tests on blood samples to determine whether the gland is functioning normally; however, the diagnosis is based on a physical examination and the results of a blood test to determine whether the person has antithyroid antibodies, which attack the thyroid gland. The level of thyroid-stimulating hormone (TSH) is measured to be sure that hypothyroidism is not present.
No specific treatment is available for Hashimoto's thyroiditis.
Most people eventually develop hypothyroidism and then must take thyroid hormone replacement therapy for the rest of their lives. Thyroid hormone may also be useful in reducing the size of the enlarged thyroid gland. People with Hashimoto's thyroiditis should avoid excess iodine (which can cause hypothyroidism) from natural sources, such as kelp tablets and seaweed.
Subacute Painful Thyroiditis: Subacute painful thyroiditis, which is probably caused by a virus, usually begins suddenly. In this disorder, inflammation causes the thyroid gland to release excessive amounts of thyroid hormones, resulting in hyperthyroidism, almost always followed by transient hypothyroidism and finally normal thyroid function.
Subacute painful thyroiditis often follows a viral illness and begins with what many people call a sore throat but actually proves to be neck pain localized to the thyroid. Many people with subacute painful thyroiditis feel extremely tired. The thyroid gland becomes increasingly tender, and the person usually develops a low-grade fever (99 to 101° F). The pain may shift from one side of the neck to the other, spread to the jaw and ears, and hurt more when the head is turned or when the person swallows. Subacute painful thyroiditis is often mistaken at first for a dental problem or a throat or ear infection.
Most people recover completely from this type of thyroiditis. Generally the thyroiditis resolves by itself within a few months, but sometimes it comes back or, more rarely, damages enough of the thyroid gland to cause permanent hypothyroidism.
Aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) can relieve the pain and inflammation. In severe cases, a doctor may recommend corticosteroids, such as prednisone, which are tapered off over 6 to 8 weeks. When corticosteroids are discontinued abruptly or too early, symptoms often return in full force. When symptoms of hyperthyroidism are severe, a beta-blocker may be recommended.
Subacute Painless Thyroiditis: Subacute painless thyroiditis occurs most often among women, typically just after childbirth, and causes the thyroid to become enlarged without becoming tender. The disorder recurs with each subsequent pregnancy. For several weeks to several months, a person with subacute painless thyroiditis has hyperthyroidism followed by hypothyroidism before eventually recovering normal thyroid function.
Hyperthyroidism may require treatment for a few weeks, often with a beta-blocker, such as propranolol. During the period of hypothyroidism, the person may need to take thyroid hormone, usually for no longer than a few months. However, hypothyroidism becomes permanent in about 10% of people with subacute painless thyroiditis, and these people must take thyroid hormone for the rest of their lives.
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