Most thyroid hormone is bound to proteins in the blood. This seems to allow it to travel around the bloodstream safely and acts as a sort of store.
A tiny proportion of thyroid hormone is not bound to protein - this is called Free. (For T3, there is around 300 times as much bound T3 as free. I cannot remember the proportions for T4, but I think even more is bound.)
Total T3 is all the bound T3 as well as all the free T3.
Total T4 is all the bound T4 as well as all the free T4.
Your Free Triiodothyronine (FT3) needs to be greater than 5.4 pmol/l
Below 5.4 pmol/l you are at risk from Dilated Cardiomyopathy (DCMP) [Congenital Heart Failure] and Diabetes. Low FT3 encourages Apoptosis of the pancreatic beta-cells (the ones that make insulin) and inhibits beta-cell proliferation.
Below 5.4 pmol/l Dendritic Cells fail to mature and carry out their unique function of directing naive "T" cells ~ This means that your immune system is screwed and "T" cells can attack anything in sight, such as the Thyroid Gland and Pancreatic Beta-Cells.
The only Thyroid Hormone you need to concentrate on is Free Triiodothyronine (FT3)
All that stuff about TSH and FT4 and being "Normalised" is a smokescreen. Yes we need Free Thyroxine (FT4) at a level above 17.0 pmol/l but it is the active hormone FT3 which is truly of importance. too little and every cell in the body is damaged.
Whilst you are at it, you need a Ferritin above 100 micro doodahs per litre. The discipline of Renology has already stated that absolute iron deficiency is a Ferritin less than 100 micrograms/litre: We need iron for deiodinase enzymes D1 & D2 to convert Thyroxine (T4) to Triiodothyronine (T3)
The UK medical profession has joined the Dork Side and is relying on the Farce to cause untold misery.
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