Anti-microsomal antibody test measures antibodies present in the blood. The thyroid cells have microsomes inside them. When the thyroid cells are damaged, the body produces antibodies to these microsomes. Also, an enzyme is generally found in the thyroid gland, which is thyroid peroxidase (TPO). This enzyme plays a special role in the production of thyroid hormones. It is also affected by antibodies when the thyroid gland is damaged. It is why the anti-microsomal antibody test is also called the thyroid peroxidase test.

The presence of the antithyroid microsomal antibodies suggests that it is associated with the thyroid glands’ autoimmune conditions. Some of these thyroid diseases include Hashimoto’s thyroiditis and Grave’s disease, wherein the immune system breaks down and produces antibodies against the thyroid gland.


When a patient is diagnosed to be positive of having anti-microsomal antibodies, it may indicate an autoimmune condition or thyroid disease. Here are some of the conditions together with their distinct symptoms:

  • Hashimoto’s Thyroiditis is a condition wherein the thyroid function is reduced due to swelling of the thyroid glands.
  • Grave’s disease is an autoimmune disease wherein the thyroid gland is overactive.
  • Subacute thyroiditis is characterized by swelling of the thyroid gland, followed by an upper respiratory infection.
  • Nontoxic nodular goiter, a condition wherein cysts called nodules appear in the thyroid gland, making it enlarged.
  • Sjogren’s syndrome is an autoimmune disease wherein the tear and saliva-producing glands are damaged.
  • Autoimmune hemolytic anemia is characterized by a drop in the number of red blood cells due to increased attacks by the immune system.
  • Thyroid cancer



Here are some of the common signs that indicate antimicrosomal antibodies are present in the body. It is best to consult the doctor if it is suspected that there is an underlying thyroid disease, and if these symptoms are present. 

  • Hyperthyroidism
  • Dry skin
  • Hair loss
  • Rapid heart rate
  • Anxiety
  • Sleeping disorders
  • Sudden weight gain or loss
  • Tremors
  • Fatigue
  • Protruding eyes
  • Intolerance to cold weather
  • Constipation


The anti-microsomal antibody test is performed by obtaining a blood sample from the patient. It is not required for the patient to undergo fasting before the procedure. However, the doctor must be informed if the patient is currently taking prescription medication or other over-the-counter medications and supplements.

There are two results for the anti-microsomal antibody test: negative and positive. If the result is negative, it means that the patient had a normal result. Normal means that the levels of anti-microsomal antibodies are of little clinical significance. Still, the presence of these antibodies may be a potential risk of developing the disease. Depending on the antibody concentration, the doctor may recommend some treatment plans or medications to prevent the antibody concentration from becoming higher. 

On the other hand, if the result is positive, it means that the patient has moderate to high anti-microsomal antibody levels. But it doesn’t mean that the patient automatically has thyroid disease. The doctor may monitor the patient longer to identify the condition accurately.



When the patient is positive to have anti-microsomal antibodies, more diagnostic tests will be conducted to identify if the patient has thyroid disease and what kind of disease it is. Blood testing may be required regularly until the condition is under control. Treatment plans will be provided by the doctor once an accurate diagnosis of the underlying disease is known.

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