Thyroglobulin Antibody, Serum Clinical Information Discusses
physiology, pathophysiology, and general clinical aspects, as
they relate to a laboratory test Thyroglobulin autoantibodies
bind thyroglobulin (Tg), a major thyroid-specific protein. Tg
plays a crucial role in thyroid hormone synthesis, storage, and
release. Noniodinated Tg is actively transported from thyrocyte
cytosol to the thyroid follicular lumen. At the extracellular
apical villae-follicular luminal interface, thyroid peroxidase
(TPO) catalyzes the iodination of tyrosine and thyronine
residues of Tg. This is followed by intramolecular coupling of
pairs of mono- and diiodotyrosines to form thyroid hormones,
predominately thyroxine (T4) or, to lesser degree,
triiodothyronine (T3). The iodinated Tg is stored in the
follicular lumen, forming the colloid. For thyroid hormone
release, colloid is reabsorbed at the apical membrane and
proteolyzed. Iodinated tyrosine residues are deiodinated and
recycled for synthesis of new Tg molecules, while the bul