Thyroiditis is an inflammation (not an infection) of the thyroid gland. Several types of thyroiditis exist, and the treatment is different for each.
Hashimoto's thyroiditis, also called autoimmune or chronic lymphocytic thyroiditis, is the most common type of thyroiditis. It is named after the Japanese physician, Hakaru Hashimoto, who first described it in 1912.
Hashimoto's thyroiditis is the most common cause of hypothyroidism. Learn about the basics of hypothyroidism in our hypothyroidism slideshow.
The thyroid gland is always enlarged in Hashimoto's thyroiditis, although only one side may be enlarged enough to feel. During the course of this disease, the cells of the thyroid becomes inefficient in converting iodine into thyroid hormone and "compensate" by enlarging (for a review of this process see our thyroid function page).
The radioactive iodine uptake may be paradoxically high while the patient is hypothyroid because the gland retains the ability to take-up or "trap" iodine even after it has lost its ability to produce thyroid hormone.
As the disease progresses, the TSH (thryoid stimulating hormone) increases since the pituitary is trying to induce the thyroid to make more hormone, the T4 (a different thyroid hormone) falls since the thyroid can't make it, and the patient becomes hypothyroid. This sequence of events can occur over a relatively short span of a few weeks or may take several years.
De Quervain's Thyroiditis
De Quervain's thyroiditis (also called subacute or granulomatous thyroiditis) was first described in 1904 and is much less common than Hashimoto's thyroiditis. The thyroid gland generally swells rapidly and is very painful and tender.
The gland discharges thyroid hormone into the blood and the patients become hyperthyroid; however, the gland quits taking up iodine (radioactive iodine uptake is very low), and the hyperthyroidism generally resolves over the next several weeks.
Silent thyroiditis is the third and least common type of thyroiditis. It was not recognized until the 1970s, although it probably existed and was treated as Graves' disease before that.
This type of thyroiditis resembles in part Hashimoto's thyroiditis and in part De Quervain's thyroiditis. The blood thyroid test is high and the radioactive iodine uptake is low (like De Quervain's thyroiditis), but there is no pain and needle biopsy resembles Hashimoto's thyroiditis. The majority of patients have been young women following pregnancy.
The disease usually needs no treatment, and 80% of patients show complete recovery and return of the thyroid gland to normal after 3 months. Symptoms are similar to Graves' disease except milder. The thyroid gland is only slightly enlarged and exophthalmos (development of "bug eyes") does not occur.
Treatment is usually bed rest with beta blockers to control palpitations (drugs to prevent rapid heart rates). Radioactive iodine, surgery, or antithyroid medication is never needed. A few patients have become permanently hypothyroid and needed to be placed on thyroid hormone.