A thyroid antibody test measures the level of thyroid antibodies in a sample of your blood. Your thyroid is a small, butterfly-shaped gland in your neck. It makes hormones that control many activities in your body, including your heart rate and how fast you burn calories from food.
Antibodies are proteins that your immune system makes to fight foreign substances, such as viruses and bacteria. But sometimes antibodies attack the healthy cells of your own tissues and organs by mistake. This is called autoimmune disease .
If antibodies attack your thyroid, they can cause serious thyroid autoimmune diseases:
- Hashimoto's disease, also known as Hashimoto's thyroiditis, is the most common cause of hypothyroidism (underactive thyroid). Hypothyroidism happens when your thyroid doesn't make enough thyroid hormones to meet your body's needs. Thyroid hormones affect the way your body uses energy. So, without enough thyroid hormones, many of your body's functions slow down.
- Graves' disease is the most common cause of hyperthyroidism (overactive thyroid). With hyperthyroidism, your thyroid makes more thyroid hormones than your body needs. This causes many of your body's functions to speed up.
If your health care provider has diagnosed you with hypothyroidism or hyperthyroidism, thyroid antibody tests can help find out if a thyroid autoimmune disease is causing the problem. There are different tests that check for different types of thyroid antibodies. Your provider will choose tests for you based on your symptoms, the results of other tests, and information about your medical history and family health history.
Other names: thyroid autoantibodies, thyroid peroxidase antibody, TPO, anti-TPO, antithyroid microsomal antibody, thyroid- stimulating immunoglobulin, TSI, TSH receptor antibody, Long-acting thyroid stimulator, LATS, TSH receptor-binding inhibitory immunoglobulin, Human thyroid stimulator