 | | | | Medical Health Encyclopedia | | Experts do not know, however why the immune system starts the process that injures the thyroid. Some theories are the following: - One theory starts with a virus that has a protein resembling a thyroid protein. During an infection, T cells induce B cells to secrete specific antibodies that attack the invasive viral protein. Unfortunately, the T cells are also tricked into inducing a B-cell attack on the similar thyroid protein.
- Genetic factors most likely play some role in autoimmune thyroiditis. For example, many patients with Hashimoto's thyroiditis express a gene called the Fas gene, which interacts with thyroid cells and trigger a process called apoptosis, in which the cells begin to self-destruct. The Fas gene is linked to genes that regulate tumor necrosis factors, which are products of the immune system that trigger a damaging inflammatory response in cells.
- In some women, thyroid autoimmunity may have developed while they were pregnant. In such cases, some evidence suggests that fetal cells accumulated in the mother's thyroid gland, triggering an immune attack.
- In some cases of Hashimoto's thyroiditis, antibodies block a receptor on thyroid cells that binds to thyrotropin (TSH). This effect is more likely to be involved in worsening the disorder, but does not explain initial destruction.
- Some evidence suggests that excess iodine intake triggers the process leading to Hashimoto's thyroiditis.
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Hashimoto's Thyroiditis. The most common form of hypothyroidism in the US is Hashimoto's thyroiditis, a genetic disease named after the Japanese doctor who first described thyroid inflammation in 1912. It occurs in approximately 0.3 to 5 people per 1,000 per year, and women are 15 to 20 times more likely than men to develop this disease.  |
Click the icon to see an image of Hashimoto's thyroiditis. |
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