Thyroglobulin is the glycoprotein precursor of the iodinated thyroid hormones thyroxine (T4) and triiodothyronine (T3). It is synthesized by thyrocytes and transported to the apical surface where it is secreted into the lumen of thyroid follicles and stored as the major component of colloid. This antibody is useful in identification of thyroid carcinoma of the papillary and follicular types. In combination with TTF1 it covers the majority of thyroid neoplasms in an immunohistochemistry panel.