Thyroglobulin (Tg) is a protein produced by the thyroid gland. This test measures the amount of thyroglobulin in the blood.
The thyroid gland produces hormones (thyroxine or T4 and triiodothyronine or T3) that help to regulate the rate at which the body uses energy. It is a small, butterfly-shaped organ that lies flat against the windpipe in the throat and is composed primarily of very small, ball-shaped structures called follicles that produce and store thyroglobulin.
Thyroglobulin serves as the source of T4 and T3. The production of these hormones and their release into the bloodstream are stimulated by the pituitary hormone TSH (thyroid stimulating hormone).
Thyroglobulin is produced in all healthy individuals, and normally its concentration in blood is very low. Thyroglobulin concentration increases in both benign (Graves disease, subacute thyroiditis, Hashimoto thyroiditis) and malignant conditions (thyroid adenoma, thyroid papillary and follicular cancer). Therefore, it is on one hand a non-specific indicator of a thyroid dysfunction and, on the other hand, a tumor marker that can be used to monitor patients with thyroid papillary and follicular cancer after diagnosis