Thyroid UK
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Thyroid Control System

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

3 Replies

I have literally skimmed through that paper - the second one - and have to say, my initial feeling is that this is the paper I have been waiting for. Will have to read properly and digest but for now (and I might easily have missed things of great importance):

o... Some form of simulation has long seemed to me the only way of actually getting things right. The whole thing is too complicated for anyone to fully understand - even at today's level of understanding.

o... They do not appear to consider the high level of thyroid innervation and what impact that might have.

o... They do take note of the variable glycolsylation levels of TSH which I feel might be important.

o... I did not notice any mechanism proposed for controlling the Free/Bound levels of T4 or T3.

Strikes me that if the TSH-only approach were appropriate then you should be able to do this:

Get a decent number of triple test results (that is, TSH, fT4 and fT3);

Give these results to a qualified endocrinologist with one or two columns blanked out;

Get the endocrinologist to make a decent estimate of the missing/hidden results.

To be fair, you would only use results from patients who appear to be fairly stable. And only from one laboratory to avoid any "different ranges" issues.

I'd bet a lot money that there would be many glaring mistakes. And yet, in practical terms, we are actually expecting ordinary non-specialist GPs to work from TSH only!

One day, we will get a simulation that can run adequately on a smartphone...



Rod, I will be interested in your thoughts once you have time to digest the article. I also need to read it again, and again. Between these two articles and Tata's on receptor signaling,

I don't see how anyone could believe that we have a complete, or even adequate understanding of how the system fully works. PR


We are already in contact with Rudolph Hoermann - watch this space! :-)


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