Anti-thyroglobulin antibody (anti-Tg) test
Quick answer: This test checks for antibodies against thyroglobulin, a protein made by the thyroid gland. Doctors order it to look for autoimmune thyroid disease such as Hashimoto's thyroiditis, often along with TPO antibodies.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
- In fertility careThyroid antibodies can matter before and during pregnancy, so your doctor may watch your thyroid levels more closely if they are positive.
How the test is done
- 1You can usually come at any time of day
- 2The skin over a vein is cleaned
- 3A needle draws a blood sample
- 4The lab checks for thyroglobulin antibodies
What your results can mean
Reading your report
A positive result is read with your TSH and thyroid hormone levels, so discuss it with your doctor.
If the result is outside the usual range
A positive result can be seen with autoimmune thyroid conditions such as Hashimoto's thyroiditis or Graves' disease. Some people with positive antibodies have normal thyroid function and are simply watched over time.
Who usually has this test
People with an underactive or overactive thyroid, a swollen thyroid, and women planning pregnancy or IVF with thyroid concerns.
Risks and aftercare
A small bruise may appear; you can carry on as usual afterwards.
Names and options
Also called: ATG, anti-Tg, thyroglobulin antibodies
Listed by the hospital as
- ANTI THYROGLOBULIN ANTIBODY, (ATG), SERUM
Questions about this test
What is the difference between anti-Tg and anti-TPO antibodies?
Both are signs of autoimmune thyroid disease. TPO antibodies are more commonly used, and anti-Tg is often checked alongside them or in people followed after thyroid cancer.
Do positive thyroid antibodies affect pregnancy?
They can be linked with a higher chance of thyroid problems during pregnancy. Your doctor may check your thyroid levels more often.
Why is anti-Tg checked after thyroid cancer treatment?
These antibodies can interfere with the thyroglobulin test used to watch for cancer returning. Knowing your antibody level helps your doctor read that test.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
Reception
Waiting area
IVF lab
This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.