The primary use of serum Thyroglobulin (Tg) measurements is as a tumor marker for monitoring reoccurrence and progression of patients diagnosed with differentiated thyroid carcinoma (DTC) following surgery and radioiodine therapy.
It is not useful for the initial diagnosis and screening for DTC. A variety of hyperactive thyroid states show increased levels of thyroglobulin (goiter, hyperthyroidism, newborns and pregnancy).