Chronic thyroiditis is swelling (inflammation) of the thyroid gland that often results in reduced thyroid function (hypothyroidism).

Chronic thyroiditis or Hashimoto's disease is a common thyroid gland disorder. It can occur at any age, but is most often seen in middle-aged women. It is caused by a reaction of the immune system against the thyroid gland.

The disease begins slowly. It may take months or even years for the condition to be detected. Chronic thyroiditis is most common in women and people with a family history of thyroid disease. It affects between 0.1% and 5% of all adults in Western countries.

Hashimoto's disease may, in rare cases, be associated with other endocrine disorders caused by the immune system. Hashimoto's disease can occur with adrenal insufficiency and type 1 diabetes. In these cases, the condition is called type 2 polyglandular autoimmune syndrome (PGA II).

Less commonly, Hashimoto's disease occurs as part of a condition called type 1 polyglandular autoimmune syndrome (PGA I), along with:

• Adrenal insufficiency
• Fungal infections of the mouth and nails
• Hypoparathyroidism

• Constipation
• Difficulty concentrating or thinking
• Dry skin
• Enlarged neck or presence of goiter
• Fatigue
• Hair loss
• Heavy and irregular periods
• Intolerance to cold
• Mild weight gain
• Small or shrunken thyroid gland (late in the disease)

Other symptoms that can occur with this disease:

• Joint stiffness
• Weight gain (unintentional)
• Swelling of the face

Note: There may be no symptoms.

Laboratory tests to determine thyroid function include:

• Free T4 test (low)
• Serum TSH (high)
• T3 (low or normal)
• Thyroid autoantibodies:
  • Antithyroid peroxidase antibody
  • Antithyroglobulin antibody

Imaging studies are generally not needed to diagnose Hashimoto's thyroiditis.

This disease may also change the results of the following tests:

• Complete blood count
• Radioactive iodine uptake
• Serum prolactin
• Serum sodium
• Total cholesterol

A lack of thyroid hormone may develop. You may receive thyroid hormone replacement therapy (levothyroxine) if your body is not producing enough of the hormone. Or, you may receive it if you have signs of mild thyroid failure (such as elevated TSH). This condition is also known as subclinical hypothyroidism.

If there is no evidence of thyroid hormone deficiency, you may just need regular observation by a health care provider.

The outcome is usually very good. The disease stays stable for years. If it does slowly progress to thyroid hormone deficiency (hypothyroidism), it can be treated with thyroid replacement therapy.

This condition can occur with other autoimmune disorders. In rare cases, thyroid cancer may develop.

Call your health care provider if you develop symptoms of chronic thyroiditis.

There is no known way to prevent this disorder. Being aware of risk factors may allow earlier diagnosis and treatment.

Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.