What is Autoimmune Hypothyroidism?

Misty Wiser
Misty Wiser
When the immune system reacts to the thyroid gland as invasive tissue, the result is swelling and inflammation of the thyroid gland.
When the immune system reacts to the thyroid gland as invasive tissue, the result is swelling and inflammation of the thyroid gland.

The thyroid disorder autoimmune hypothyroidism (AH) is caused when the immune system regards the thyroid gland as invading tissue. Antibodies are released to attack the gland, resulting in the inflammation and enlargement of the thyroid. Production of the thyroid hormone thyroxine decreases even when the pituitary gland produces higher levels of thyroid-stimulating-hormone (TSH). It is treated with a daily synthetic thyroid replacement medication.

Very rarely, a myxedema coma is caused by severe autoimmune hypothyroidism.
Very rarely, a myxedema coma is caused by severe autoimmune hypothyroidism.

Autoimmune hypothyroidism is also called Hashimoto’s disease or chronic autoimmune thyroiditis. A severe form of the condition is called primary myexdema or autoimmune atrophic thyroiditis. These conditions are suspected to be genetic because there is a higher incidence of autoimmune hypothyroidism seen among the family members of a person with a confirmed diagnosis of AH.

Swollen legs or feet and muscle pain may plague some with autoimmune hypothyroidism.
Swollen legs or feet and muscle pain may plague some with autoimmune hypothyroidism.

The symptoms of autoimmune hypothyroidism are sometimes mistaken for another condition. Early indicators of a developing thyroid problem are extreme fatigue and dry skin. The thyroid gland may swell, causing a bulging area on the throat, called a goiter. A swollen thyroid gland may cause difficulty swallowing when eating or drinking. Most people with this thyroid disorder gain weight or develop a puffy-looking face and body, a condition called myxedema.

A low amount of absorbed iodine indicates that the thyroid is not functioning properly.
A low amount of absorbed iodine indicates that the thyroid is not functioning properly.

Many people also report having digestive troubles, including constipation. Swollen legs or feet and muscle pain may plague some with autoimmune hypothyroidism. A person may be more likely to develop infections or feel extreme sensitivity to cold temperatures after the thyroid gland quits functioning properly. Women may have menstrual irregularities.

Severe cases of autoimmune hypothyroidism may cause serious health risks. The possibility of heart failure increases and the organ may become enlarged. Fluid may collect around the lungs and cause shortness of breath.

Very rarely, a myxedema coma is caused by severe autoimmune hypothyroidism. It begins with a sudden drop in body temperature. The heart rate then slows down, a condition called bradycardia. Eventually the patient loses consciousness and falls into a coma. Emergency medical treatment should be obtained for any person exhibiting these symptoms.

Diagnosis of autoimmune hypothyroidism usually follows a blood test and a physical examination of the neck for evidence of a goiter. Blood tests will show elevated levels of antibodies to an enzyme called thyroid peroxidase, high TSH levels, and low thyroxine levels. A thyroid scan may be done to confirm the diagnosis.

The thyroid scan process requires two separate scans done within 24 hours of each other. About four hours before the first scan, a small radioactive iodine pill will need to be swallowed. The scan will reveal any inflammation of the thyroid gland and the amount of iodine that has been absorbed into the thyroid gland. A low amount of absorbed iodine indicates the thyroid gland is not functioning properly.

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    • When the immune system reacts to the thyroid gland as invasive tissue, the result is swelling and inflammation of the thyroid gland.
      When the immune system reacts to the thyroid gland as invasive tissue, the result is swelling and inflammation of the thyroid gland.
    • Very rarely, a myxedema coma is caused by severe autoimmune hypothyroidism.
      Very rarely, a myxedema coma is caused by severe autoimmune hypothyroidism.
    • Swollen legs or feet and muscle pain may plague some with autoimmune hypothyroidism.
      Swollen legs or feet and muscle pain may plague some with autoimmune hypothyroidism.
    • A low amount of absorbed iodine indicates that the thyroid is not functioning properly.
      A low amount of absorbed iodine indicates that the thyroid is not functioning properly.