Front. Endocrinol., 21 March 2018 | doi.org/10.3389/fendo.2018....
Mathematical Modeling of the Pituitary–Thyroid Feedback Loop: Role of a TSH-T3-Shunt and Sensitivity Analysis
Julian Berberich, Johannes W. Dietrich, Rudolf Hoermann and Matthias A. Müller
This is a highly and I mean highly complicated theoretical paper from my colleagues + some systems analyst experts from Mercedes Benz in Stuttgart. However what it shows in summary is that the known circadian rhythm for FT3 that lags behind the same rhythm for TSH can only be explained by a TSH-controlling conversion of T4 into T3 INSIDE THE WORKING THYROID. This means that in health the thyroid doesn't just supply T4 for the body to make T3 but also controls the overall T3 production by finetuning the system overall against unwanted surges. It is also important in several other relationships between TSH, and thyroid hormone supply. I did indicate its presence in short form earlier but it is now available in complete form.
Therefore this demonstrates what an important function is lost when the thyroid dies and how oral therapy cannot make up for it.