Thyroglobulin test

[gassy]

Hi Dr.Mark

I had a thyroglobulin AB test done and the result was 476 - normal range was <115. August I did have a ANA test, that was negative, what is the difference between these 2 tests are they not both for antibodies? Why would one come back neg. and one come back with high number over the normal. I have been diagnosed hypo however my TSH has been from 0.07 -7.63. I was on 175 mcg levothyroxine sodium then my Dr. decreased meds to 100 mcg. Ultrasound - small thyroid - no nodules. On my right side legs and arms are bruising could this be because of the thyroglobulin test coming back high for antibodies? I also still have the tightness & pain in my neck and throat by my thyroid gland. Any imput is greatly appreciated.

Louise

[Mark Lupo, M.D.]

There are several different antibodies that can be tested in the body - they are specific to different proteins or cells.  Thyroglobulin is a thryoid protein - so the positive antibody is consistent with Hashimotos.  The ANA tests for an antibody against the nucleus of a cell -- this is a different test and do not have to overlap.  The ANA identifies patients with diseases such as lupus.

That's quite a wide TSH range and the decrease from 175 to 100 is steep -- I would recheck the TSH 6 weeks after the change then change the dose if necessary - typically we move one dose at a time (100,112,125,137,150,175,200,etc).  I target a TSH of about 1.0 in most patients.

I don't think the bruising is due to thyroid antibodies.  If the thyroid is small on u/s then the tightness is unlikely to be the cause of the neck and throat pain - consider reflux or allergies as an alternative.

[Heather123]

I had high thyroglobulin antibodies and have been trying to figure out exactly what that means.  One thyroid book I'm reading says:

ATA - (Antithyroid antibodies) test
This is used to test for the presence of antibodies that attack the thyroid gland.  To test for Hashimoto's thyroiditis, doctors test for two kinds of autoantibodies in the blood.  
Antithyroglobulin antibody (TgAb) damages and destroys thyroglobulin (the main storage protein for thyroid hormones) and interferes with the production of thyroid hormone.  
Antiperoxidase antibody (TPOAb) disrupts the enzyme peroxidase, which is involved in maintaining the delicate chemical balance necessary for thyroid hormone to be made and activated.

Sooo, if you have one of these that are elevated you have Hashimoto's?  I also read that the TgAb test is used to check on thyroid cancer, but if you have a really high level it doesn't necessarily mean you have cancer.  Then I read that most people have antibodies running through them but not all of them are out of control.  

Sooo, I am a little confused.  My TSH was 2.83 in Feb, 6.3 @ the beginning of September, 4.99 mid September...my TgAb was 105 (normal 20).  My TPOAb was fine (18, s/b under 35).  
What exactly does this all mean?  Am I hypo but not that bad?  The antibodies are attacking and I'm trying to fight them off, but I'm doing so-so???