Hashimoto’s disease, also called chronic lymphocytic thyroiditis or autoimmune thyroiditis, is an autoimmune disease. An autoimmune disease is a disorder in which the body’s immune system attacks the body’s own cells and organs.
Normally, the immune system protects the body from infection by identifying and destroying bacteria, viruses, and other potentially harmful foreign substances.
In Hashimoto’s disease, the immune system attacks the thyroid gland, causing inflammation and interfering with its ability to produce thyroid hormones. Large numbers of white blood cells called lymphocytes accumulate in the thyroid. Lymphocytes make the antibodies that start the autoimmune process.
Hashimoto’s disease often leads to reduced thyroid function, or hypothyroidism. Hypothyroidism is a disorder that occurs when the thyroid doesn’t make enough thyroid hormone for the body’s needs.
Thyroid hormones regulate metabolism—the way the body uses energy—and affect nearly every organ in the body. Without enough thyroid hormone, many of the body’s functions slow down. Hashimoto’s disease is the most common cause of hypothyroidism in the United States.
What are the symptoms of Hashimoto’s disease?
Many people with Hashimoto’s disease have no symptoms at first. As the disease slowly progresses, the thyroid usually enlarges and may cause the front of the neck to look swollen.
The enlarged thyroid, called a goiter, may create a feeling of fullness in the throat, though it is usually not painful. After many years, or even decades, damage to the thyroid causes it to shrink and the goiter to disappear.
Not everyone with Hashimoto’s disease develops hypothyroidism.
For those who do, the hypothyroidism may be subclinical—mild and without symptoms, especially early in its course. With progression to hypothyroidism, people may have one or more of the following symptoms:
- weight gain
- cold intolerance
- joint and muscle pain
- constipation, or fewer than three bowel movements a week
- dry, thinning hair
- heavy or irregular menstrual periods and problems becoming pregnant
- memory problems
- a slowed heart rate
What causes Hashimoto’s thyroiditis?
Hashimoto’s thyroiditis is a condition caused by inflammation of the thyroid gland. It is an autoimmune disease, which means that the body inappropriately attacks the thyroid gland – as if it was foreign tissue.
The underlying cause of the autoimmune process remains unknown. Hashimoto’s thyroiditis tends to occur in families. It can be associated with other autoimmune conditions such as type 1 diabetes or celiac disease.
Hashimoto’s thyroiditis is 5 to 10 times more common in women than in men and most often starts in adulthood. Blood drawn from people with Hashimoto’s thyroiditis typically reveals an increased number of antibodies against thyroid-specific proteins, including thyroperoxidase and thyroglobulin.
T lymphocytes, a type of cell involved in the inflammation process, invade the thyroid gland cause silent, painless inflammation that destroys it; ultimately, the individual produces little or no thyroid hormone and becomes hypothyroid.
Who is more likely to develop Hashimoto’s disease?
Hashimoto’s disease is much more common in women than men. Although the disease often occurs in adolescent or young women, it more commonly appears between 30 and 50 years of age.
Hashimoto’s disease tends to run in families. Researchers are working to identify the gene or genes that cause the disease to be passed from one generation to the next.
Possible environmental factors are also being studied. For example, researchers have found that consuming too much iodine may inhibit thyroid hormone production in susceptible individuals.
Chemicals released into the environment, such as pesticides, along with certain medications or viral infections may also contribute to autoimmune thyroid diseases.
People with other autoimmune diseases are more likely to develop Hashimoto’s disease. The opposite is also true—people with Hashimoto’s disease are more likely to develop other autoimmune diseases.
These diseases include
- vitiligo, a condition in which some areas of the skin lose their natural color.
- rheumatoid arthritis, a disease that causes pain, swelling, stiffness, and loss of function in the joints when the
- immune system attacks the membrane lining the joints.
- Addison’s disease, in which the adrenal glands are damaged and cannot produce enough of certain critical hormones.
- type 1 diabetes, in which the pancreas is damaged and can no longer produce insulin, causing high blood glucose, also called blood sugar.
- pernicious anemia, a type of anemia caused by not having enough vitamin B12 in the body. In anemia, the number of red blood cells is less than normal, resulting in less oxygen carried to the body’s cells and extreme fatigue.
- celiac disease, a form of gastrointestinal gluten sensitivity, an autoimmune disorder in which people cannot tolerate gluten because it will damage the lining of the small intestine and prevent adsorption of nutrients.
- Gluten is a protein found in wheat, rye, and barley and in some products.
- autoimmune hepatitis, or nonviral liver inflammation, a disease in which the immune system attacks liver cells.
How is Hashimoto’s disease diagnosed?
Diagnosis begins with a physical exam and medical history. A goiter, nodules, or growths may be found during a physical exam, and symptoms may suggest hypothyroidism.
Health care providers will then perform blood tests to confirm the diagnosis. A blood test involves drawing blood at a health care provider’s office or a commercial facility and sending the sample to a lab for analysis. Diagnostic blood tests may include the
TSH test. The ultrasensitive TSH test is usually the first test performed. This test detects even tiny amounts of TSH in the blood and is the most accurate measure of thyroid activity available. Generally, a TSH reading above normal means a person has hypothyroidism.
T4 test. The T4 test measures the actual amount of thyroid hormone circulating in the blood. In hypothyroidism, the level of T4 in the blood is lower than normal.
antithyroid antibody test. This test looks for the presence of thyroid autoantibodies, or molecules produced by a person’s body that mistakenly attack the body’s own tissues.
Two principal types of antithyroid antibodies are
anti-TG antibodies, which attack a protein in the thyroid called thyroglobulin anti-thyroperoxidase (TPO) antibodies, which attack an enzyme called thyroperoxidase in thyroid cells that helps convert T4 to T3.
Having TPO autoantibodies in the blood means the body’s immune system attacked the thyroid tissue in the past. Most people with Hashimoto’s disease have these antibodies, although people whose hypothyroidism is caused by other conditions do not.
A health care provider may also order imaging tests, including an ultrasound or a computerized tomography (CT) scan.
Ultrasound. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure.
A specially trained technician performs the procedure in a health care provider’s office, an outpatient center, or a hospital, and a radiologist—a doctor who specializes in medical imaging—interprets the images; a patient does not need anesthesia.
The images can show the size and texture of the thyroid, as well as a pattern of typical autoimmune inflammation, helping the health care provider confirm Hashimoto’s disease. The images can also show nodules or growths within the gland that suggest a malignant tumor.
CT scan. CT scans use a combination of x rays and computer technology to create images. For a CT scan, a health care provider may give the patient a solution to drink and an injection of a special dye, called contrast medium.
CT scans require the patient to lie on a table that slides into a tunnel-shaped device where the x rays are taken. An x-ray technician performs the procedure in an outpatient center or a hospital, and a radiologist interprets the images. The patient does not need anesthesia.
In some cases of Hashimoto’s disease, a CT scan is used to examine the placement and extent of a large goiter, and to show a goiter’s effect on nearby structures.
How does Hashimoto’s disease affect pregnant women?
During pregnancy, hypothyroidism is usually caused by Hashimoto’s disease and occurs in three to five out of every 1,000 pregnancies.2 Uncontrolled hypothyroidism raises the chance of miscarriage, premature birth, stillbirth, and preeclampsia—a dangerous rise in blood pressure in late pregnancy.
Untreated hypothyroidism during pregnancy may also affect the baby’s growth and brain development. Thyroid medications can help prevent these problems and are safe to take during pregnancy.
Women with Hashimoto’s disease should discuss their condition with their health care provider before becoming pregnant.
What is the treatment of Hashimoto’s thyroiditis?
There is no cure for Hashimoto’s thyroiditis. The timeframe of the autoimmune process and inflammation will continue is not predictable. In the vast majority of patients, hypothyroidism results from the inflammatory process.
Thyroid hormone medication can replace the hormones the thyroid made before the inflammation started. There are two major thyroid hormones made by a healthy gland (T3 and T4).
Replacing one or both of these hormones can alleviate the symptoms caused by the absolute or relative lack of hormones as a consequence of Hashimoto’s thyroiditis.
Without medication, there is very little chance the thyroid would be able to maintain hormone levels within the normal range, and symptoms and signs of hypothyroidism would occur or worsen.
If you think you may have Hashimoto’s thyroiditis, ask your doctor to check your thyroid function and order blood tests to help make a diagnosis.
If you know you have Hashimoto’s thyroiditis, continue to take medications as directed by your physician, and follow-up regularly with your health care professional for thyroid function tests and optimal care.