A blood sample is needed.

You may be told not to eat or drink anything for several hours (usually overnight). Your health care provider may monitor you or tell you to stop taking certain medicines for a short time before the test because they may affect the test results. DO NOT stop taking any medicine without first talking to your provider.

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.

This test helps detect possible thyroid problems.

Antithyroglobulin antibodies can be a sign of thyroid gland damage caused by the immune system. They may be measured if thyroiditis is suspected.

Measuring thyroglobulin antibody levels after treatment for thyroid cancer can help your provider decide what the best test is to monitor you for a recurrence of the cancer.

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

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

A positive test means antithyroglobulin antibodies are found in your blood. They may be present with:

• Graves disease or overactive thyroid
• Hashimoto thyroiditis
• Subacute thyroiditis
• Underactive thyroid
• Systemic lupus erythematosus
• Type 1 diabetes

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

If you have a positive test for antithyroglobulin antibodies, this may make it harder to measure your thyroglobulin level accurately. Thyroglobulin level is an important blood test to determine risk that thyroid cancer will recur.

There is little risk involved with having your blood taken. 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
• Multiple punctures to locate veins
• Hematoma (blood buildup under the skin)
• Infection (a slight risk any time the skin is broken)