Every now and then you run across a study where they are actually trying to understand the complexity of the thyroid system. This is from 2004 in Hot Thyroidology and the authors are from the Univ. of Bristol. PR
"Despite 100 years of thyroid hormone replacement, controversy still exists about the optimum replacement therapy for hypothyroid patients. Several recent studies have given insight in to the complex thyroid hormone metabolism. These support the hypothesis that serum and tissue levels of thyroid hormones may diverge significantly and vary between tissues. The dissatisfaction experienced by some individuals on thyroxine replacement despite normal TSH levels may in part relate to this. If so, it should be seen as a pointer to greater understanding of the action of thyroid hormone and its predisposing effects on morbidity in many conditions rather than an unwelcome clinical frustration. If so, we are the beginning of a road of discovery rather than at the end of an unsuccessful chapter in thyroid hormone replacement."
Admin Edit to change heading from CAPS