Thyroid Autoimmune?

Thanks so much for your response.  I don't believe I ever had a test to see if my Hypo-Thyroid was autoimmune.  What test do I need to get to find that out?  Also, what does an anti-GAD and anti-islet cell antibody test for?  And what are c-peptide levels?  Thanks so much for all your help.

[Anita Ramsetty, MD]

Hi,
In regard to the thyroid autoimmunity testing: the two tests we use are anti-thyroglybulin antibodies and anti-TPO antibodies. There are other autoimmune tests as well but these are the most common and will usually give you your answer.

The Anti-GAD and anti-islet cell antibodies test for autoimmune defects that can lead to type 1 diabetes.  Some people test positive but do not develop diabetes for a long time, others can have Type 1 diabetes and not test positive at some point in time. So they are not perfect tests, but they are overall quite good.
C-peptide is a protein that is part of our insulin molecule, so the levels are a good reflection of what we make on our own. If the levels are low at a time we would expect to have insulin in our system, then it usually means our production is low, and thus insulin replacement may be necessary in future. All type 1's have low c-petide levels, and some type 2's also do(they require insulin treatment because their pancreas will not respond to pills.)
Hope  this helps.
Take care.