Antithyroid microsomal antibody
Thyroid antimicrosomal antibody; Antimicrosomal antibody; Microsomal antibody; Thyroid peroxidase antibody; TPOAb
Microsomes are found inside thyroid cells. The body produces antibodies to microsomes when there has been damage to thyroid cells. The antithyroid microsomal antibody test measures these antibodies in the blood.
Antibodies
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
How the Test is Performed
A blood sample is needed.
Blood sample
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
This test is done to confirm the cause of thyroid problems, including Hashimoto thyroiditis .
Hashimoto thyroiditis
Chronic thyroiditis is caused by a reaction of the immune system against the thyroid gland. It often results in reduced thyroid function (hypothyroi...
The test is also used to find out if an immune or autoimmune disorder is damaging the thyroid.
Autoimmune disorder
An autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 types of aut...
Normal Results
A negative test means the result is normal.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
A positive test may be due to:
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Granulomatous thyroiditis
Granulomatous thyroiditis
Subacute thyroiditis is an immune reaction of the thyroid gland that often follows an upper respiratory infection. The thyroid gland is located in th...
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Hashimoto thyroiditis
Hashimoto thyroiditis
Chronic thyroiditis is caused by a reaction of the immune system against the thyroid gland. It often results in reduced thyroid function (hypothyroi...
High levels of these antibodies have also been linked with an increased risk of:
- Miscarriage
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Preeclampsia
Preeclampsia
Preeclampsia is when a pregnant woman develops high blood pressure and protein in the urine after the 20th week of pregnancy.
- Premature birth
- In vitro fertilization failure
Important: A positive result does not always mean that you have a thyroid condition or that you need treatment for your thyroid. A positive result may mean that you have a higher chance of developing thyroid disease in the future.
Antithyroid microsomal antibodies may be seen in your blood if you have other autoimmune conditions, including:
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Autoimmune hemolytic anemia
Autoimmune hemolytic anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to the body's tissues. Red blo...
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Autoimmune hepatitis
Autoimmune hepatitis
Autoimmune hepatitis is inflammation of the liver. It occurs when immune cells mistake the liver's normal cells for harmful invaders and attack them...
- Autoimmune adrenal disease
- Rheumatoid arthritis
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Sjögren syndrome
Sjögren syndrome
Sjögren syndrome is an autoimmune disorder in which the glands that produce tears and saliva are destroyed. This causes dry mouth and dry eyes. The...
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Systemic lupus erythematosus
Systemic lupus erythematosus
Systemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the body's immune system mistakenly attacks healthy tissue. It can af...
Risks
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood buildup under the skin)
- Infection (a slight risk any time the skin is broken)
References
Salvatore D, Davies TF, Schlumberger MJ, et al. Thyroid physiology and diagnostic evaluation of patients with thyroid disorders. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, Larsen PR, et al, eds. Williams Textbook of Endocrinology . 12th ed. Philadelphia, PA: Elsevier; 2016:chap 11.
Weiss RE, Refetoff S. Thyroid function testing. In: Jameson JL, De Groot LJ, eds. Endocrinology: Adult and Pediatric . 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 78.
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Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
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Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
Review Date: 2/3/2016
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.