This test measures the amount of thyroglobulin (Tg) in the blood. Tg is a protein produced by follicle cells in the thyroid gland. The thyroid gland is a small butterfly-shaped organ that helps to regulate the rate at which the body uses energy. The thyroid lies flat against the windpipe in the throat and is composed primarily of very small, ball-shaped structures called follicles. Cells in the follicles produce and store Tg, breaking it down as needed into the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine). The production of these hormones and their release into the blood stream is stimulated by the pituitary hormone TSH (thyroid stimulating hormone). No other part of the body makes Tg, but it is produced by many thyroid cancers – both those confined to the thyroid gland and those that have spread to other parts of the body. The Tg test is primarily used as a tumor marker to evaluate the effectiveness of treatment for thyroid cancer and to monitor for recurrence. Not every thyroid cancer will produce Tg, but the most common types (papillary and follicular thyroid cancer) that arise from the follicle cells frequently do - resulting in increased levels of Tg in the blood. Tg may be ordered, often along with a TSH test, prior to thyroid cancer treatment to determine whether the cancer is producing Tg.
If it is, then it can be measured again after the completion of treatment to evaluate the effectiveness of treatment and may be ordered at intervals to monitor for cancer recurrence. Several Tg levels may be ordered over a period of time (serial samples) to look at the change in concentration. The change often provides more information than a single value.
Enzyme Immunoassay, Chemiluminescence
Sandwich Assay, Streptavidin-Coated Plate
0, 2.0, 10.0, 40, 100, 250 ng/ml
Short Procedure 125 Minutes