2 different type TGab testings done- can't find answer to, anyone know?

[Allie323]

Does anyone know the difference between these two tests they are both for thyroglobulin antibodies or is one for auto -anti bodies or that's the same thing? They seem like different methodologies, but this new she -doctor's test has me in range. I'm always high TG.. I have Hashimoto's.

My GPS and endocrine always test me for TPO and a Tg. The new doctor ran a Thyroglobulin (LCMS) test or by a "Labcorp" lab here in states.

Any thoughts? thanks!

My usual endochrine/ GP tests are

TPO. Ab 202 <9.0 IU/ML

TG. 349. <4.0IU/ML

Her Tests. April 20

TPO 176...(0-34 IU/ML)Thyroglobulin LCMS 3.4 ng/mL. (1.5-38.5)

[helvella Administrator Thyroid UK]

Thyroglobulin test and Thyroglobulin antibodies are different tests.

Measurement of Thyroglobulin by LC-MS/MS in Serum and Plasma in Presence of Anti-Thyroglobulin Autoantibodies

ncbi.nlm.nih.gov/pmc/articl...

[Allie323 in reply to helvella]

Yes, thanks I did see that and read it.. Got the impression that one test can give a negative result?

I still can't figure out the difference.

...is there two simpler definitions

I was going to write the doctor and ask her why she didn't do the other one but since I don't know the difference LOL....

Which one do I need or not need.

[helvella Administrator Thyroid UK in reply to Allie323]

One measures the protein thyroglobulin.

The other measures antibodies to thyroglobulin.

You could have two negatives, two positives, or one negative and one positive - either way round.

Both can be relevant. Without knowing what was going through her mind, I really don't know why she chose the testing she did.

[Allie323]

Helvella ... thanks, you know more than I do! But which definition goes with which? What are their abreviations? And could you explain a little more how they are relevant to each other? I think I would need the one that is the antibody (because of Hashimoto's) that measures antibodies to the thyroglobulin. I got 349 result for that prior. Is that one abbreviated Tg Ab? (<4 sometimes its lower 280 etc.(She is actually a pediatrician! and GP... A friend's referral I went to, to check out.)

[helvella Administrator Thyroid UK]

TGab (might have different capitals) is Thyroglobulin antibodies. Your immune system is producing antibodies to the protein thyroglobulin. This is a measure of how many. If above the test's lower limit, it is a positive test.

The units vary - often, as in your post, International Units per Millilitre.

Thyroglobulin is described here:

labtestsonline.org.uk/tests...

Or here

labtestsonline.org/tests/th...

Both sites also explain further about why you might have both tests done.

[Allie323]

Ok. I will check it out, thanks!