Thyroglobulin Human

Thyroglobulin is a dimeric protein with a molecular weight of approximately 660 kDa . It is synthesized in the rough endoplasmic reticulum of thyroid follicular cells and then secreted into the follicular lumen, where it accumulates in the colloid . Each thyroglobulin molecule contains around 2768 amino acids and includes multiple tyrosine residues that are essential for hormone synthesis .

The primary function of thyroglobulin is to serve as a precursor for the thyroid hormones thyroxine (T4) and triiodothyronine (T3) . These hormones are produced through the iodination and coupling of tyrosine residues within the thyroglobulin molecule. The iodinated thyroglobulin is then proteolytically cleaved to release T4 and T3 .

Thyroglobulin levels in the serum can be indicative of various thyroid disorders. Elevated levels of thyroglobulin are often found in conditions that disrupt thyroid tissue, such as Hashimoto’s disease, Graves’ disease, thyroid adenoma, subacute thyroiditis, and thyroid carcinoma .

In the context of thyroid cancer, thyroglobulin serves as a valuable tumor marker. After a total or near-total thyroidectomy and successful radioiodine ablation, the serum thyroglobulin level should drop to very low or undetectable levels . A rise in thyroglobulin levels can indicate a recurrence of the disease .

Thyroglobulin testing is commonly used in the follow-up of patients with differentiated thyroid carcinoma. It helps in monitoring the effectiveness of treatment and detecting any recurrence of the disease . The reference range for thyroglobulin levels in the serum is typically less than 55 ng/mL .

The gene encoding thyroglobulin is located on chromosome 8 in humans . It is highly expressed in the thyroid gland and plays a critical role in thyroid hormone biosynthesis . Mutations in the thyroglobulin gene can lead to congenital hypothyroidism and other thyroid-related disorders .