Most doctors have no knowledge of post-thyroid deficiencies. And while TSH may be a good indicator of thyroid gland deficiencies, it substantially removed from post-thyroid deficiencies -- particularly what is occuring in the cells' nuclei. Remember the action is not TSH in the blood, but T3 in the nuclei -- paraphrasiing Dr. E. Chester Ridgway.....
Please note (per Saravanan, et al.) that 13% of all those treated for hypothyroidism are not satisfied with their hypothyroiidsm therapy. They may need several things -- more thyroxine, a T3-containing hormone replacement, or a different hormone replacement.
What medicine does, however, is declare that the very symptoms that prompted an investigation for deficient thyroxine are not sufficient to prompt any investigation in the deficiency of any other hormone.
So if you were one of 13% you might take hope upon reading Baisier, et al., and their use of different diagnostics and therapies.
WOW - big words for a simple answer LOL
Because most doctors feel looking at a TSH number to decide a thyroid condition is better than looking at a T3.
That's it.
I saw the petition a while back.