Myxedema in hypothroidism (Hashimoto's)

[pathtopenn]

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Why is there myxedema in HYPOthyroidism? I understand the reasoning for HYPERthroidism b/c the autoimmune cause the lymphocyte to sec more fx which cause the fibroblasts behind the eye to oversecrete GAGs which cause edema behind the eyes.

What exactly is the pathogenesis for hypothroidism derived myxedema?

Thanks for the help!

 

[VisionaryTics]

In Graves' disease, the antibodies are stimulating the TSH receptors.

In Hashimoto's, endogenous TSH is stimulating the TSH receptors (low T3/T4 due to autoimmune destruction -> lack of negative feedback -> high TSH -> myxedema).

 

[pathtopenn]

In Graves' disease, the antibodies are stimulating the TSH receptors.

In Hashimoto's, endogenous TSH is stimulating the TSH receptors (low T3/T4 due to autoimmune destruction -> lack of negative feedback -> high TSH -> myxedema).

I am sorry but could u please explain more in depth the high TSH -> myxedema. This is where I am stuck on. I would like to know the the mechanism of how this is being done. I was under the impression that T3/T4 is what is stimulating the lymphocytes to oversec fibroblast fx which is making the GAG to be produced double-time.

 

[Zenfudge]

I am sorry but could u please explain more in depth the high TSH -> myxedema. This is where I am stuck on. I would like to know the the mechanism of how this is being done. I was under the impression that T3/T4 is what is stimulating the lymphocytes to oversec fibroblast fx which is making the GAG to be produced double-time.

The fibroblasts (i.e. orbital fibroblasts) possess TSH receptors. If you have more TSH floating around, you'll have further stimulation of the fibroblasts to secrete GAGs.

Talks about the receptor expression:

http://www.ncbi.nlm.nih.gov/pubmed/7523481

Basically says TSH has a regulatory role in collagen synth - interestingly (and expectedly), if you have hypothalmic hypothyroidism with low TSH, the increase GAGs shouldn't occur.

http://www.ncbi.nlm.nih.gov/pubmed/19826182

That's my two cents - I only glanced at the abstracts.


Thanks to the Visionary - I never actually fully understood this process myself - my school phoned the explanation in.