If oral thyroid hormone supplement is administered, is the attack stopped or does it just create an excess of thyroid hormones so that even after a lot of it is destroyed by the antibodies, there is still enough for normal bodily functions?

  • $\begingroup$ Welcome to Bio. Where did you hear that thyroid hormones are targets for antibodies? Could you add that source in the question? $\endgroup$
    – AliceD
    Feb 13 '16 at 6:04
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    $\begingroup$ Thank you. It was based on a misunderstanding.My endocrinologist just said that the antibodies attack the "thyroid". While he might have thought it's obvious that "thyroid" means the the "thyroid gland" ,for someone with very basic knowledge in biology like me, it either meant the "thyroid hormones" or the "thyroid gland".I had previously asked a question here on stack which was based on this misunderstanding and the responses that I got made me realize that something wasn't right.This question was intended to get things completely straight and to clarify a few things( as you can see ). $\endgroup$ Feb 13 '16 at 13:57

Hashimoto's Thyroiditis is an autoimmune disorder where autoreactive attack on the actual thyroid tissue results in hypothyroidism. Pyzik et al., 2015, provides a good review of what we know about HT. The prevailing theory is that nonspecific infection can induce HLA expression on thyroid cells through the action of interferon gamma.

HLA is an antigen-presenting complex in humans that in our case is the major histocompatibility complex II or MHC-II you will see in texts (to avoid confusing names). Processed segments of protein are loaded onto the MHC-II, and displayed to the extracellular space where T cells positive for CD4 can recognize them. CD4+ T cells, upon recognition of MHC-II, are stimulated into T-helper or Th cells that are specific for the protein antigen they found on the MHC-II. The problem with MHC-II expressed by thyrocytes and the like is they can load either foreign or self peptides, so if it loads a part of thyroglobulin (Tg) on there and that's what the T cell recognizes, it's going to produce an immune response specific for Tg in a complex series of downstream events.

Being said, supplementation of thyroid hormone is a good treatment for hypothyroidism but it won't stop the attack on the actual gland. Thyroid hormones aren't often attacked by autoimmunity because they aren't protein antigens, and different subsets of cells respond to non-peptide antigens.

  • $\begingroup$ Thank you so much! So,ultimately would the entire thyroid gland be destroyed bit by bit and will the patient have to completely rely on supplements ? $\endgroup$ Feb 5 '16 at 16:44
  • $\begingroup$ It can boil down to that. Cases/treatments vary and one of the things you have to watch out for during the course of HT are malignant B cell clones in the actual thyroid, in which case excision of the entire gland might be necessary. A medical doctor will know the best route of treatment for a given patient. $\endgroup$
    – CKM
    Feb 5 '16 at 17:44
  • $\begingroup$ I've an appointment with an endocrinologist but it's not in another couple of weeks.I decided to get a head start here and I am glad I did. Just one last question though. Is there anything that can actually suppress the antigen attack like maybe a drug or leading a very healthy lifestyle ? $\endgroup$ Feb 6 '16 at 10:13

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