Hashimoto's thyroiditis

Definition

Thyroiditis is inflammation of the thyroid gland, a butterfly-shaped organ next to the windpipe.

Description

The thyroid is the largest gland in the neck. It produces, secretes, and stores thyroxine (T₄), a hormone that influences the metabolism of just about every body process.

When the thyroid gland is functioning properly, hormone release is carefully regulated. When bacteria or viruses invade and inflame the gland, T₄ surges into the bloodstream and raises hormone levels that then discourage the gland from creating more T₄. Eventually the hormone stores are exhausted, the thyroid loses its ability to manufacture T₄, and an underactive thyroid (hypothyroidism) results.

The major cause of hypothyroidism, thyroiditis affects about 12 million people in the United States. This condition is more common in women than in the men and usually develops between ages 30-50.

Hashimoto's disease

The most common type of thyroiditis is Hashimoto's disease, a painless disorder also known as:

• Autoimmune thyroiditis
• Chronic lymphocytic thyroiditis
• Lymphadenoid goiter
• Struma lymphomatosa.

Hashimoto's disease can develop at any age, but is most common in middle-aged women. This immune-system disorder runs in families, and affects about 5% of adults in the United States.

Hashimoto's disease slowly destroys thyroid tissue and robs the gland of its ability to change iodine into T₄. The condition progresses so gradually that many people who have it do not realize anything is wrong until the enlarged gland forms a goiter, a swelling seen and felt in the front of the neck. This may not happen until weeks or even years after an individual develops Hashimoto's.

Subacute thyroiditis

Much less common than Hashimoto's disease, subacute thyroiditis is a painful inflammation that develops suddenly in a patient who has had a viral infection, such as mumps or an upper respiratory illness. Pain radiates throughout the neck and patients feel ill and feverish. It may take as long as several months for normal thyroid function to resume.

Subacute thyroiditis is also called:

• DeQuervain's thyroiditis
• Giant cell thyroiditis
• Granulomatous thyroiditis
• Subacute granulomatous thyroiditis.

Silent thyroiditis

The least common of the three major types, silent thyroiditis is characterized by rigidity and slight enlargement of the thyroid gland. Postpartum thyroiditis, a form of silent thyroiditis, develops in 5-9% of all women who have recently given birth. Postpartum thyroiditis develops within a year of the baby's birth and disappears within six months.

Acute thyroiditis

Caused by acute infection, this rare disease is a medical emergency. A patient who has acute thyroiditis has a high fever and feels very ill. The neck is red, hot, and very tender.

Causes & symptoms

Hashimoto's disease

Hashimoto's disease develops when the immune system attacks the thyroid gland. It may be related to such hormone-related (endocrine system) disorders as:

• Addison's disease. This condition, caused by malfunction of the adrenal gland, is characterized by weakness, loss of weight and appetite, and increased sensitivity to cold.
• Diabetes mellitus. This metabolic disorder is caused by a lack of insulin production or by the body's inability to process insulin.
• Grave's disease. This disease is the most common form of hyperthyroidism.
• Vitiligo. This is a noncancerous skin disease characterized by unpigmented patches of skin.

Being female and having a family history of Hashimoto's thyroiditis increases the likelihood of developing the disease. Its symptoms include:

• Constipation
• Fatigue
• Goiter or enlarged neck
• Inability to tolerate cold temperatures
• Weight gain. Some patients' faces swell and their joints stiffen.

Subacute thyroiditis

Characterized by painful gland enlargement that is sometimes mistaken for a sore throat that may last for months, subacute thyroiditis often follows:

• Influenza
• Mumps
• Upper respiratory infections
• Viruses that produce cold symptoms and inflammation of the membrane that protects the brain (meningitis), inflammation of the sac that surrounds the heart (pericarditis), inflammation of the heart muscle (myocarditis), and other diseases.

People who have subacute thyroiditis feel feverish, weak, and tired. The thyroid is sore to the touch. They may be nervous, sweat, and have trouble tolerating heat or swallowing. Symptoms of subacute thyroiditis also include:

• Rapid heartbeat
• Tremors
• Weight loss.

Silent thyroiditis

The cause of silent thyroiditis is uncertain, but the condition is believed to be an immune-system disorder triggered by childbirth. Although silent thyroiditis is painless, the condition's other symptoms are similar to those of subacute thyroiditis. The thyroid gland enlarges only slightly, and the eyes do not bulge.

Diagnosis

Family physicians and endocrinologists usually base a diagnosis of thyroiditis on:

• Blood levels of thyroid hormones, thyroid-stimulating hormone, and anti-thyroid antibodies
• Personal and family medical history
• The appearance of a patient's thyroid gland.

Thyroid antibodies present in 95% of patients with Hashimoto's thyroiditis make it possible to diagnose this disease without surgery or biopsy. A blood test that measures sedimentation rate, an indication of the extent of inflammation, is a useful tool for diagnosing subacute thyroiditis.

Treatment

Medical therapy for thyroiditis includes:

• Antibiotics to fight infection
• High doses of aspirin to relieve inflammation
• Hormones to suppress or replace thyroid function
• Pain medications.

Cortisone drugs are sometimes prescribed to reduce persistent inflammation. In rare instances, surgery can be used to drain infection or relieve pressure near the thyroid gland.

Hashimoto's disease

The goal of treatment for Hashimoto's disease is to prevent the thyroid gland from getting larger. Regular monitoring may be the only treatment indicated for patients whose gland is only slightly enlarged, and who show no signs of hormone deficiency. Levothyroxine (Synthroid) may be prescribed to correct hormone deficiency in a patient who has a large goiter.

Subacute thyroiditis

The goal of treatment for subacute thyroiditis is to relieve pain, reduce inflammation, and regulate hyperthyroidism. Bed rest and beta blockers (Propranolol, Naldolol) may be necessary until thyroid activity is controlled, and the patient may have to take:

• Anti-inflammatory medication for several weeks
• High doses of aspirin
• Other analgesics.

If subacute thyroiditis continues for a long time, cortisone and thyroid hormone medication may be prescribed to relieve inflammation and allow the gland to rest. Glucocorticoids (Prednisone) are prescribed for symptoms that do not respond to other treatment. The original problem often becomes more pronounced after these medications are discontinued.

Silent thyroiditis

Most patients who have silent thyroiditis don't need any treatment, but:

• Bed rest and beta blockers are occasionally needed to regulate rapid heart beat.
• Inderal (Propanolol) may be prescribed for brief periods of hyperthyroidism.
• Steroids may be prescribed for severe episodes of acute inflammation.

Acute thyroiditis

Acute thyroiditis requires emergency treatment with antibiotics and surgery.

Prognosis

Thyroiditis usually responds to treatment, and some patients recover normal thyroid function without treatment. Because permanent loss of thyroid function is a possibility and life-long thyroid replacement therapy may be necessary, regular medical monitoring should continue even after the patient has apparently recovered.

Hashimoto's disease

Some cases of Hashimoto's disease remain stable for years. Others slowly progress to hypothyroidism, which is treated with thyroid hormone replacement therapy.

Subacute thyroiditis

Most patients with subacute thyroiditis recover fully after no more than a few months. This condition occasionally recurs, but severe or long-term complications are rare.

Silent thyroiditis

Four of every five patients with silent thyroiditis recover completely within three months. The thyroid status of these patients should be evaluated within 12 months. Because silent thyroiditis recurs in 10% of patients within three years and may progress to hypothyroidism, medical monitoring should continue for three years after recovery appears complete.

Prevention

Flu shots or immunizations for measles, mumps, and rubella may help prevent conditions associated with subacute thyroiditis. There is no known way to prevent other forms of thyroiditis.

Key Terms

Addison's disease

A disease that results from a deficiency in adrenocortical hormones.

Diabetes mellitus

A disorder of the pancreas. This chronic disorder of carbohydrate metabolism results in hyperglycemia and glycosuria.

Goiter

An abnormal enlargement of the thryroid gland.

Grave's disease

Also called hyperthyroidism, this disease results from overactivity of the thyroid gland.

Subacute

An abnormal condition present in a person who appears to be clinically well.

Vitiligo

A benign skin disease that results in irregular patches of skin that are totally lacking in color.

Further Reading

For Your Information

Organizations

• The Thyroid Foundation of America. 350 Ruth Sleeper Hall, Parkman Street, Boston, MA 02114. (800) 232-8321 ; (617) 726-8500. http://www.clark.net/pub/tfa/.
• The Thyroid Society for Education and Research. 7515 South Main Street, Suite 545, Houston, TX 77030. (800) THYROID; (713) 799-9909. http:the-thyroid-society.org/thyroid.html.

  Other

• Chronic thyroiditis (Hashimoto's disease). http://www.healthanswers.com/database/ami/converted/000371.html. (30 April 1998).
• How do doctors test for thyroiditis? http://the-thyroid-society.org/faq/15html. (25 April 1998).
• The Merck Manual. Silent Thyroiditis. http://www.merck.com/!!uZ2hZOM//3uZ2hZOM13/pubs/mmanual/html. (22 April 1998).
• The Merck Manual. Subacute Thyroiditis. http://www.merck.com/!!tkNH50WWitKNXA1CWP/pubs/mmanual/html/qgmkhij.htm. (22 April 1998).
• Postpartum Thyroiditis. http://www.clark.net/pub/tfa/postbrochure.html. (20 April 1998).
• Subacute thyroiditis. http://healthanswers.com/database/ami/converted/000375.html. (30 April 1998).
• Thyroiditis. http://www.thriveonline/health/Library/illsymp/illness 522.html. (21 April 1998).
• What are the main types of thyroiditis? http://the-thyroid-society.org/faq/13html. (20 April 1998).
• What is thyroiditis? http://the-thyroid-society.org/faq104.html. (20 April 1998).
• Your thyroid. http://www.endocrineweb.comthyroid.html. (22 April 1998).

Gale Encyclopedia of Medicine. Gale Research, 1999.