Thyroglobulin Antibody (TgAb) Quantity

Thyroglobulin antibodies (TgAb) are immune proteins directed against thyroglobulin, the protein the thyroid uses to make hormone. Elevated TgAb is a marker of autoimmune thyroid disease, most often Hashimoto's thyroiditis, which presents with fatigue, weight gain, cold intolerance, dry skin, and an enlarged thyroid. TgAb has a second important role in people treated for differentiated thyroid cancer: a rising or newly appearing level can signal recurrence, while a steady decline suggests successful treatment, and TgAb must be measured alongside any thyroglobulin (Tg) test because it interferes with Tg readings. Note that roughly 10% of the general population carries detectable TgAb, so a low-level positive is not automatically pathological and is read against TSH, symptoms, and TPO antibodies.

This is the quantitative version, reporting a concentration in IU/mL, which makes it the right choice for tracking trends over time, such as monitoring thyroglobulin antibody change after thyroid cancer treatment. The separate TgAb Presence test gives only a positive or negative answer; the TPO and Thyroglobulin Antibodies panel adds the second autoimmune antibody, which is often the more sensitive marker for Hashimoto's.