What Is an Anti-thyroglobulin Antibody Test?

    Your thyroid is an endocrine gland located in your neck. It is responsible for releasing hormones that control your metabolism. The thyroid gland produces a number of different proteins, including thyroglobulin. This protein helps produce the hormones released by the thyroid gland.

    The presence of an autoimmune system disorder can cause disruptions in how this protein is produced. Autoimmune disorders occur when your immune system begins attacking your healthy cells and tissues. When your immune system attacks thyroglobulin, a corresponding antibody is produced. This antibody is known as the antithyroglobulin antibody. The antithyroglobulin antibody test is used to measure whether or not you have this antibody in your bloodstream.

    The antithyroglobulin antibody test is also known as:

    • thyroid autoantibody
    • antithyroid antibody
    • antimicrosomal antibody
    • TPOAb
    • Anti-TPO
    • TBII
    • TgAb

    Why Is an Antithyroglobulin Antibody Test Ordered?

    Your doctor may order the antithyroglobulin antibody test if you have symptoms of a thyroid disorder. Symptoms of thyroid disorders include:

    • fatigue
    • unexplained weight gain
    • dry skin
    • constipation

    Your doctor may also order this test if you develop a condition known as goiter. Goiter occurs when your thyroid gland becomes enlarged. The test may also be ordered if you have an autoimmune disorder, such as Graves disease or Hashimoto thyroiditis. Impaired thyroid function may develop if you have these conditions.

    How Is the Antithyroglobulin Antibody Test Administered?

    The antithyroglobulin antibody test is typically administered by a nurse or lab technician in a clinical setting. You will simply be required to provide a blood sample. The blood sample is commonly extracted through the arm with a small needle. The blood will be collected in a tube and sent to a lab for analysis. Once the results are reported by the lab, your doctor will be able to provide you with more information about your results and what they mean.

    What Are the Risks of the Test?

    If you have an antithyroglobulin antibody test, you may experience some discomfort when the blood sample is drawn. Needle sticks may result in pain at the puncture site. After the test, you may experience pain or throbbing at the insertion site.

    In general, the risks of the antithyroglobulin test are minimal. These risks are common to all routine blood tests. Potential risks of the test include:

    • difficulty obtaining a sample, resulting in multiple needle sticks
    • excessive bleeding at the puncture site
    • fainting or lightheadedness
    • the accumulation of blood under the skin, known as a hematoma
    • development of an infection where the skin is broken by the needle

    Preparing for the Test

    Your doctor will tell you what you need to do to prepare for the test. Typically, you will be required to fast (not to eat or drink anything for several hours before the test). Your doctor may recommend that you take nothing by mouth after midnight the night before.

    There are certain medications that may interfere with the results of the test, especially blood thinners, such as warfarin. You may need to stop taking these medications before you have this test. Talk with your doctor about all medications you are taking, including prescription and non-prescription drugs. Do not stop taking your medications until you talk with your doctor.

    Understanding the Test Results

    Normal results for the antithyroglobulin antibody test are negative. This means that there are no antibodies present in your bloodstream. If you do have small amounts of the antithyroglobulin antibody in your blood, this may indicate the presence of certain health problems, including:

    If you have high levels of the antibody in your blood, this may indicate additional health problems, such as the presence of serious autoimmune disorders, including:

    • Graves disease
    • Hashimoto thyroiditis

    Though the presence of antithyroglobulin antibodies typically indicates a serious health problem, there are instances in which these antibodies are present without any specific complications. Antithyroglobulin antibodies have been found to increase in women as they age, but without any corresponding health problems.

    If you have these antibodies with no underlying cause, your doctor may monitor your health and antibody levels to make sure that you do not develop any serious problems.