Antibody to thyroglobulin (anti-Tg)
Thyroglobulin (Tg) is produced in the thyroid gland and is a main component in the lumen of the thyroid follicle. In synergy with the enzyme thyroid‑specific peroxidase (TPO), Tg has an essential function in the iodination of L‑tyrosine and in the formation of the thyroid hormones T4 and T3. Both Tg and TPO are potentially autoantigenic.
Elevated serum concentrations of antibodies against Tg (Tg‑autoantibodies) are found in subjects with autoimmunity‑based thyroiditis. High concentrations of anti‑Tg together with anti‑TPO are indicative of chronic lymphocytic‑infiltrative thyroiditis (Hashimoto's disease). The frequency of thyroglobulin antibodies is approx. 70‑80 % in subjects with autoimmune‑thyroiditis, including Hashimoto's disease, and approx. 30 % in individuals with Graves' disease. The anti‑Tg assay is important for use in monitoring the course of Hashimoto's thyroiditis and for the differential diagnosis (cases of suspected autoimmune thyroiditis of unknown origin with negative anti‑TPO test results, Graves' disease without lymphocytic infiltration, and to rule out interference by Tg‑autoantibodies in the Tg test).
Although the sensitivity of the procedure can be increased by simultaneously determining additional thyroid antibodies (anti‑TPO, TSH‑receptor‑antibodies), a negative result does not definitively rule out the presence of an autoimmune disease. The level of the antibody titer does not correlate with the clinical activity of the disease. Titers that are elevated initially can become negative if the disease persists for a longer period of time or if remission occurs. If antibodies reappear after remission, a relapse is likely
SI units Conversion Calculator. Convert Antibody to thyroglobulin (anti-Tg) level to IU/mL, kIU/L. Clinical laboratory units online conversion from conventional or traditional units to Si units. Table of conversion factors for Antibody to thyroglobulin (anti-Tg) unit conversion to IU/mL, kIU/L.