Autoimmune thyroiditis, is a chronic disease in which the body interprets the

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...

glands and its

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...

products T3, T4 and TSH as threats, therefore producing special antibodies that target the thyroid's cells, thereby destroying it. It may present with hypothyroidism or hyperthyroidism and with or without a

goiter A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly. Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...

Signs and symptoms

The symptoms may vary depending on the thyroid function, i.e.

hyperthyroidism Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidis ...

or hypothyroidism. Hyperthyroidism can cause sweating, rapid heart rate, anxiety, tremors, fatigue, difficulty sleeping, sudden weight loss, and protruding eyes. Hypothyroidism can cause weight gain, fatigue, dry skin, hair loss, intolerance to cold, and constipation. The effects of this disease may be permanent but can sometimes be transient. Symptoms may come and go depending on whether the person receives treatment, and whether the treatment takes effect.

Causes

Thyroid autoimmunity is familial. The disease is said to be inherited as a dominant trait since it has been reported that as many as fifty percent of the first degree relatives of patients with some type of autoimmune thyroiditis present with thyroid antibodies in serum. Few studies have even related it to chromosome 21 because of its high correlation with patients with

Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...

and familial Alzheimer disease. This theory is controversial, since patients with

Turner syndrome Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic condition in which a female is partially or completely missing an X chromosome. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low hair ...

also present a high prevalence of autoimmune thyroiditis (up to fifty percent).

High iodine consumption

Autoimmune thyroiditis has a higher prevalence in societies that have a higher intake of iodine in their diet, such as the United States and Japan. Also, the rate of lymphocytic infiltration increased in areas where the iodine intake was once low, but increased due to iodine supplementation. "The prevalence of positive serum tests in such areas rises to over 40 percent within 0.5 to 5 years."

Age

It has been shown that "the prevalence of positive tests for thyroid antibodies increases with age, with a frequency as high as 33 percent in women 70 years old or older." The mean age of prevalence in women is higher than in men by one year, (58 and 59 years old respectively).Autoimmune thyroiditis can affect children. It is very rare in children under the age of five, but can occur; it accounts for around 40 percent of cases in adolescents with goiters. People with hypothyroidism over the age of 40 have an increased chance of developing autoimmune thyroiditis.

Mechanism

Thyroid autoantibodies appear mostly with the presence of lymphocytes in the targeted organ. Lymphocytes produce antibodies targeting three different thyroid proteins:

Thyroid peroxidase Thyroid peroxidase, also called thyroperoxidase (TPO) or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine re ...

Antibodies (TPOAb),

Thyroglobulin Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment ...

Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb). The antibody attacks ultimately lead to hypothyroidism, which is caused by replacement of follicular cells with parenchymatous tissue. Some patients who are healthy may be positive for more than one of these antibodies. Doctors who attend to such patients will most likely do routine follow-ups on the patient's health since, even though it is highly unlikely that they will present any thyroid problems, there is still a chance that they will develop some type of dysfunction with time.

Diagnosis

Various tests can be chosen depending on the presenting symptoms. Doctors may search for Thyroid peroxidase Antibodies (TPOAb) when a person has symptoms of hypothyroidism, or when a person will be started on a drug therapy associated with risks of developing hypothyroidism, such as

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...

Interferon alfa Interferon alfa (INN) or HuIFN-alpha-Le, trade name Multiferon, is a pharmaceutical drug composed of natural interferon alpha (IFN-α), obtained from the leukocyte fraction of human blood following induction with Sendai virus. Interferon alfa con ...

. This antibody is related to

and Graves' disease. If the person presents symptoms of hyperthyroidism, doctors are more likely to test for Thyroid stimulating hormone receptor Antibodies (TRAb), and monitor the effects of anti-thyroid therapy, also associated with Graves' disease. Doctors may check Thyroglobulin Antibodies (TgAb) also, whenever a thyroglobulin test is performed to see if the antibody is interfering. TgAb may also be ordered in regular intervals after a person has been diagnosed with thyroid cancer, and just like TPOAb, it can be associated with Hashimoto's thyroiditis.

Signs and symptoms

Causes

High iodine consumption

Age

Mechanism

Categories

Diagnosis

Treatment

References

External links