Guest guest Posted June 21, 2005 Report Share Posted June 21, 2005 To late I guess you are going to hear it whether or not you want to. LOL....anyways I will try and make this short, there are some things I was going to put in here that I can no longer find, I hope you do beleieve me when I say that I have read that receptor sensitiveity to thyroid hormone has been proven before, but I did have my doubtrs about it, I think the change would be short lived and not permanent. I did manage to find this though. " T4 can cause an equally rapid suppression of TSH via its intrapituitary conversion to T3 64,74 (Fig. 4-3). This T4 to T3 conversion process is catalyzed by the Type 2 deiodinase. (see Chapter 3). An effect of T4 per se can be demonstrated if its conversion to T3 is blocked by a general deiodinase inhibitor such as iopanoic acid 75,76. In this case, the T4 in the cell rises to concentrations sufficient to occupy a significant number of receptor sites even though its intrinsic binding affinity for the receptor is only 1/10 that of T3. A similar effect can be achieved by rapid displacement of T4 from its binding proteins by flavonoids 77. It seems likely, however, that under physiological circumstances the feedback effects of T4 on TSH secretion and synthesis can be accounted for by its intracellular conversion to T3. " Here is the entire paper http://www.pubmedcentral.nih.gov/articlerender.fcgi? tool=pubmed & pubmedid=447848 Now like any researchThe T4 suspression was not proven with all following studies....but it is pretty well accepted that the T3 in the brain is largely from local deionazation, which is not the case with the liver. I think the case that I am trying to make is that the liver can be slightly starved for hormone if on T4 only. I have heard on average that the normal ratio of T4 to T3 is about 4-1. Now I am not preaching that T4 is inadequate treatment but IMO not a lot of docs really now how to monitor thyroid treatment. When given T4 only this ratio becomes very skewed, just plain logic should tell you that, on average you are probably going to be shy on T3 by about 7-12 mcg, just a educated guess, daily. I beleieve in a small subgroup of people it is very possible that they are getting a double whammy, not only are they missing some T3 but its possible that the body is also takeing in the hugely less potent T4 and just about getting nothing out of those fireing receptors. Quote Link to comment Share on other sites More sharing options...
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