Definition

Antithyroglobulin antibody is a test to measure antibodies to a protein called thyroglobulin, which is found in thyroid cells.

Alternative Names

Thyroid antithyroglobulin antibody; Thyroglobulin antibody

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

How to prepare for the test

You may be told not to eat or drink anything for several hours before the test (usually overnight). Medications that may affect test results will be monitored or discontinued until after the test.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test helps detect possible thyroid problems. Antithyroglobulin antibodies can lead to the destruction of the thyroid gland. Such antibodies are more likely to appear after thyroid gland inflammation or injury.

Normal Values

A negative test is normal. A negative tests means no antibodies to thyroglobulin are found in your blood.

What abnormal results mean

A positive test means antithyroglobulin antibodies are found in your blood. This may be due to:

• Hashimoto's thyroiditis
• Thyrotoxicosis
• Systemic lupus erythematosus (SLE)
• Hypothyroidism
• Thyroid cancer
• Myxedema
• Grave's disease
• Type 1 diabetes

Pregnant women and relatives of those with autoimmune thyroiditis may also test positive for these antibodies.

What the risks are

Veins and arteries vary in size from one patient 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 light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

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