There is a new research paper out which again shows that the current use of TSH when thyroid patients are on thyroid hormones is flawed.
The paper shows that patients who have had total thyroidectomy are very likely to require a suppressed TSH in order to be able to give them enough T4 hormone replacement to correct their symptoms. In these athyreotic (no thyroid) cases, it is clear from the study that a suppressed TSH does not mean the patients are hyperthyroid. In fact, it is often necessary to have a suppressed TSH in order to provide enough T4 medication to get a sufficiently high FT3 level that the patient feels well.
It is also clear from the research that athyreotics (people without a thyroid or thyroid-less), are just one end of the spectrum to those with reduced thyroid hormone production. It IS a spectrum and it should be clear that simply having a very low or suppressed TSH cannot mean automatically that a thyroid patient receiving thyroid treatment is hyperthyroid.
One of the big takeaways from this is that endocrinologists and doctors should stop assuming that every time a thyroid patient has very low or near zero (suppressed) TSH on thyroid treatment that this means the person is hyperthyroid, or that they will develop heart issues or bone-loss. It simply is not true.
If someone is NOT on thyroid treatment but has a suppressed TSH then this situation is utterly different to when a patient is under treatment.
It is not a problem at all for a thyroid patient who is receiving thyroid hormone treatment to have a suppressed TSH, as long as they do not have actual hyperthyroid symptoms (or elevated FT3).
The practice of automatically reducing thyroid medication due to suppressed TSH is quite wrong. That is just a numbers game and makes no allowance for either the research or the clinical presentation of the patient.
This practice of never allowing a suppressed TSH when on thyroid medication is making the flawed assumption that you can treat thyroid patients receiving thyroid medication as if they are on no medication at all and hyperthyroid. It is quite wrong.
For those on thyroid treatment, the clinical presentation must be paramount and the use of simplistic thyroid labs must come secondary.
Here are the details on the paper:
“Heterogenous Biochemical Expression of Hormone Activity in Subclinical/
Overt Hyperthyroidism and Exogenous Thyrotoxicosis”
Rudolf Hoermann, John E.M. Midgley, Rolf Larisch, Johannes W. Dietrich
PII: S2214-6237(19)30152-8
DOI: https://doi.org/10.1016/j.jcte.2020.100219
Reference: JCTE 100219
https://www.sciencedirect.com/science/article/pii/S2214623719301528
Many thanks to John Midgley for letting me know about the paper.
Note: for those on treatment containing T3 (T3/T4 or NDT or T3-Only) TSH can easily be suppressed to near zero even though FT3 and FT4 can be in range. This is one of the flaws of the TSH test. Even Dr. Robert Utiger who created the TSH test in the first place acknowledged the highly suppressive effect of T3 containing medication. So, attempting to use TSH for those on T3 therapy in the same way as it is used for those on T4 medication is flawed.
Best wishes,
Paul
