Computed tomography of the thyroid vascular, encapsulated structure made up of right and left lobes, which are connected at the midline by the isthmus. Each lobe is about 2 cm thick, 3 cm wide, and 5 cm long. The thyroid apex is located superiorly at the level of the mid-thyroid cartilage. The inferior margin of the gland is at the level of the fifth or sixth tracheal ring. The thyroid gland is encapsulated by the middle layer of deep cervical fascia and is part of the visceral space in the infrahyoid neck. It wraps around the trachea and is separated from the oesophagus by the
Thyroid peroxidase body primarily as iodide, I. After entering the thyroid follicle (or thyroid follicular cell) via a Na/I symporter (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid via pendrin, after which thyroid peroxidase oxidizes iodide to atomic iodine (I) or iodinium (I). The "organification of iodine," the incorporation of iodine into thyroglobulin for the production of thyroid hormone, is nonspecific; that is, there is no TPO-bound intermediate, but iodination occurs via reactive iodine species released from TPO. The chemical reactions catalyzed by thyroid peroxidase occur on the outer apical membrane surface and are mediated