Our review of thyroid function in normal healthy people and the implications for future treatment in thyroid disease has been published in Frontiers in Thyroid Endocrinology. If you put into Google "Frontiers in Thyroid Endocrinology" the article should be displayed for free download. To summarise, we show that in healthy people there is a continuous change in the relations between TSH, FT4 and FT3 across the range of FT3. Those at the upper end of the healthy range are the more likely to require T3 supplementation to T4 if they become ill later. You therefore can't just lump everyone in together as being all capable to respond properly to T4 only treatment. That asumption which is the basis of current belief is wrong. Also one again the normal range for TSH in health doesn't apply on therapy what ever that is.