Why ANTI TPO and ANTI TGO test is done TPO plays an important role in the production of thyroid hormones. A TPO test detects antibodies against TPO in the blood. If you've been diagnosed with thyroid disease, your doctor may suggest a TPO antibody test and other thyroid tests to help find the cause. 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.