Pure T3 Thyroid and Stories of Recovery from Chronic Fatigue Syndrome (ME/CFS) and Fibromyalgia: An Overview.
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there are in fact three types of deiodinase enzymes that convert T4: D1 is responsible for conversion of T4 into T3 in most cells of the body, except for in the brain and the pituitary where D2 does the job (De Groot, 2015). D3 converts T4 into an inactive “reverse T3” (RT3) which (sometimes disturbingly) competes with T3 for space on the above-mentioned cells’ nuclear membrane thyroid receptors (note: D3 also converts T3 into T2; the role of this thyroid hormone is still being researched).
Critically, under certain conditions (such as inflammation, fasting or stress), D1 is downregulated and D3 is upregulated, resulting in less T3 and more RT3 at the cellular level. This can result in hypothyroid symptoms – even if the thyroid gland itself is functioning normally (Holtorf, 2014a).
the fact that some patients may have difficulty converting T4 into T3, that supplemented T4 may be converted into RT3 instead of T3, and that the transport of T4 into the cells requires more energy than the transport of T3 – may explain why therapies that contain T3 have often succeeded when T4-only therapies have failed to improve symptoms.
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I wonder if their theories can be shown on blood tests.
Although I know how Dr. Peat feels about free T4 and free T3 labs, an rT3 might be good to track in such cases.My rT3 indeed does go down when I increase my T3 while taking T4/T3.
Thank you for sharing this - I will look into their therapies further.
