Anti Thyroglobulin Antibody
What is Anti-Tg?
Your thyroid gland produces a number of proteins including thyroglobulin. This protein helps produce hormones released by thyroid. Your doctor may order a anti thyroglobulin antibody test if you have symptoms of a thyroid disorder (hypothyroidism) like fatigue, weight gain, constipation, cold intolerance or when your other thyroid tests like T3, T4, and TSH show some abnormality.
Why is Anti-Tg done?
- Prior to and after the completion of treatment for thyroid cancer to evaluate the effectiveness of treatment
- To monitor the recurrence of thyroid cancer
- If you have symptoms of hyperthyroidism like sweating, rapid heart rate, tremors, anxiety, weight loss, protruding eyes
- If you have symptoms of hypothyroidism like weight gain, fatigue, constipation, cold intolerance
- If you have another autoimmune disorder and are at increased risk of thyroid dysfunction
Interpreting Anti-Tg results
- If thyroglobulin concentrations are initially elevated in a person diagnosed with thyroid cancer, then it is likely that thyroglobulin can be used as a tumor marker. Thyroglobulin levels should be undetectable or very low after the surgical removal of the thyroid (thyroidectomy) and/or after subsequent radioactive iodine treatments. If levels are still detectable, there may be normal or cancerous thyroid tissue remaining in the person's body, indicating the need for additional treatment
- If the level of thyroglobulin is low for a few weeks or months after surgery and then begins to rise over time, then the cancer is probably recurring
- Decreasing levels of thyroglobulin in those treated for Grave's disease indicate a response to treatment
- People who have goitre, thyroiditis or hyperthyroidism may have elevated thyroglobulin levels, although this test is not routinely ordered