Autoimmune Thyroiditis - Autoimmune Thyroid Disease

Autoimmune thyroiditis, (or Chronic Autoimmune thyroiditis), is a chronic disease in which the body interprets the thyroid glands and its hormone 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.

Categories

Specialists separate autoimmune thyroiditis into two clinical categories.

1. If goiters are present, it is understood as Hashimoto’s Thyroiditis.

2. If the thyroid is atrophic, and does not present goiters, it is called atrophic thyroiditis.

It can also refer to Graves' disease. If the symptoms of thyroiditis appear in women after giving birth, it is called Postpartum thyroiditis.

Signs and symptoms

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

Genetics

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. Some studies have even related it to chromosome 21 because of its high correlation with patients with Down’s syndrome and familial Alzheimer’s disease. This theory is controversial, since patients with Turner’s syndrome 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 Antibodies (TPOAb), Thyroglobulin Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb). 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 or Interferon alfa. This antibody is related to Hashimoto's thyroiditis 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.

References