Thyroglobulin Test in Subhash Nagar West, Delhi

Thyroglobulin (Tg) is a protein made only by thyroid cells and stored in the thyroid gland, where it serves as the scaffold for making thyroid hormones. A small amount is always present in the blood when the thyroid exists. The test is used mainly as a tumour marker after treatment of differentiated (papillary or follicular) thyroid cancer.

After the thyroid is removed and remnant tissue destroyed with radioactive iodine, thyroglobulin should become very low or undetectable. A rising level suggests that thyroid tissue, possibly cancer, remains or has returned. It is not used to diagnose thyroid cancer, since levels also rise in benign goitre, thyroiditis and Graves' disease.

Anti-thyroglobulin antibodies, present in a number of patients, can interfere and give falsely low results, so anti-Tg antibody is tested at the same time. Doctors usually interpret the result with TSH levels, neck ultrasound and scans, and always follow the trend in the same laboratory.