Thyroglobulin test measures the thyroglobulin level in the blood circulation. Thyroglobulin is a kind of protein that is produced by the cells in thyroid gland. Thyroglobulin test is used to monitor thyroid cancer patients before and after surgery. Thyroglobulin test is a tumor marker and provides very important information about the patient’s condition. Also its level may increase in thyroid damage and thyroid inflammation.
Thyroglobulin production in the body
Thyroglobulin level is very low in healthy people. In normal conditions it is produced during the thyroid hormone production in the thyroid gland. Thyroid gland uses the thyroglobulin to produce tyroid hormones and it is secreted to blood circulation beside them.
How the Thyroglobulin test is done?
Thyroglobulin test is done in a blood sample. You should give a tube of blood sample. Your nurse-technician will insert a needle in a vein usually inside of your elbow or on the back of your hand. He/she will draw blood into the test tube. You may feel a little pain during the process for a few seconds. All blood collection procedure takes 1-2 minutes.
Purpose; why the Thyroglobulin test is done?
Thyroid gland is removed by surgery in thyroid cancer and after that radioactive iodine therapy is done to remove all throid tissue. Thyroglobulin level is found high before thyroid cancer surgery and decreases quickly after removal of thyroid gland. No thyroglobulin is expected in blood circulation after these stages because there will be no thyroid cells left to produce thyroglobulin after the treatment.
Thyroglobulin half-life is about 2-4 days and it is used to evaluate the response to treatment after surgery. Increasing after treatment is a sign of tumor that is can’t removed completely by surgery.Thyroglobulin should be undetectable if tumor is absent.
Thyroglobulin test can be used to diagnose factitious hyperthyroidism, it is found very low or none in this condition but high in other types of hyperthyroidism. Thyroglobulin test also useful for thyroid agnesis in newborn (congenital hypothyroidism).
Thyroglobulin test normal values
This value may change according to the laboratory, test method and the analyser
0-1 years old baby thyroglobulin: 2-110 mcg/L
1-10 years old children thyroglobulin: 2-65 mcg/L
11-20 years old children thyroglobulin: 2-36 mcg/L
21-80 years old thyroglobulin: 2-25 mcg/L
After thyroid removing surgery: Less than 0.1 ng/mL
High Thyroglobulin test results
Most patients with thyroid cancer have increased thyroglobulin result
Nontoxic nodular goiter
Low thyroglobulin result
Thyroid agenesis in newborn
Decreases after surgery, low levels after surgery is a sign of successful treatment