Many of us have had the experience of standard thyroid tests not relating to what is happening in our bodies. The 'standard model' seems to be too simplistic in many ways.
A few days ago Rod posted a link concerning the log-linear relationship between TSH and T4
and the fact it may not be so linear.
This is another article from the Journal of Thyroid Research regarding the control system.
"Methodological advances in mathematical and simulative modelling of thyroid homeostasis have led to a better understanding of static and dynamic behaviour of thyroid hormones in health and disease. Together with results from molecular and clinical research on the central role of TSH in thyroid homeostasis such progress has permitted the development of advanced methods for interpretation of laboratory results that provide previously inaccessible information on pituitary and thyroid function. A future perspective overcoming the limits of univariate reference ranges for TSH, FT4, and FT3 promises the development of approaches for personalised diagnosis of thyroid homeostasis that may also be a foundation for targeted dosing of thyroid hormone substitution."
Taken together these articles offer some hope that science is beginning to realize the complexity of the thyroid control system and the problems with current testing. PR