Lab Test and Reference Range Thyroid Treatment is Failing Patients
Lab Test and Reference Range Based Thyroid Treatment is Failing Patients.
All of this information (and a lot more besides) is in my latest book 'The Thyroid Patient's Manual'. See the following link for more details on this book: http://recoveringwitht3.com/book/thyroid-patients-manual
There are two important points that I need to make.
Firstly, and this is the most important point - thyroid lab tests all suffer from a ‘low index of individuality’. The range of variance in the population is much wider than the range of variance in the individual (this is also known as non-ergodicity). We know now from research that the actual individual person ranges for levels like FT3 and FT4 are less than half as wide as the wide population ranges that doctors are using to assess our thyroid lab results. When you make generalisations based on the population and try to apply them to the individual, you have problems. See this previous blog post for more details on this: http://recoveringwitht3.com/blog/thyroid-blood-tests-reference-ranges-ar... Basically, the lab reference range doesn't help much in assessing their result. We just don't know where their individual actual reference range is!
See: Narrow individual variations in serum T(4) and T(3) in normal subjects: a clue to the understanding of subclinical thyroid disease - Stig Anderson. See: https://academic.oup.com/jcem/article/87/3/1068/2846746 (it shows that individual person reference ranges are less than half as wide as the population lab test ranges).
Research has also shown that once patients are on thyroid treatment, the required levels of thyroid hormones are not the same as in healthy people. Your unique individual reference ranges for the different thyroid hormones may have shifted from when you were healthy. This is another huge problem that exists within the current approach to treating thyroid patients. See the following reference: Recent Advances in Thyroid Hormone Regulation: Toward a New Paradigm for Optimal Diagnosis and Treatment - Hoermann, Midgley, Larisch, Dietrich. See: https://www.frontiersin.org/articles/10.3389/fendo.2017.00364/full . This paper talks about the need for a new paradigm of thyroid treatment that accepts that the relationship between TSH and thyroid hormones are individual, dynamic and can adapt, i.e. the current practice of simply looking at numbers that do or do not fit in the population ranges is not sufficient.
Secondly, we also know that some laboratories include the data from thyroid patients with in-range TSH levels. However, thyroid patients tend to have higher FT4 and lower FT3 than non-thyroid patients. This is because the T4-Only medication does not result in as much FT3 as a healthy person has from conversion of T4, plus there is a loss of T3 from the thyroid gland itself. The net-effect of this is that the bottom and the top of the reference ranges for FT4 and FT3 are influenced by the inclusion of the thyroid patient data. As a result of this practice, you may be more likely to be considered healthy with higher inactive pro-hormone FT4 and lower biologically active FT3. I am aware of at least one thyroid researcher who is writing a paper which cites data to back this up, based on actual laboratory statistics (I previously included some of this data, but as it is not published yet, I have decided to remove it, even though it is true).
The Bottom Line
It is currently impossible to assess what the unique individual person ranges are, other than through the treatment of a thyroid patient. This is another huge issue, because in most instances, doctors are satisfied if the patient's thyroid labs sit within the population reference ranges - virtually anywhere within them!
Moreover, thyroid blood tests cannot measure the FT3, FT4 and rT3 levels within the cells. They only measure the blood portion and as such are an approximation to what might be present within the cells. Since conversion occurs within the cells we cannot know specific information about FT3, FT4 and rT3 inside the cells. So, treating symptoms and signs is key.
The bottom line is, there is not as much value to the thyroid lab reference ranges as is being assumed, and relied upon, by most doctors at the present time.
Simply having results that fit inside each lab test reference range is no guarantee of symptom relief. What is important, is finding a treatment regime that relieves your symptoms.
The response to treatment, and the changing relationships between TSH, FT4, FT3, and rT3 should be what guides dosing decisions. Sticking mechanically to the existing reference ranges without using good clinical judgement is a desperately flawed approach.
Of course we also need to have ALL the thyroid treatments available to patients, in order to ensure every individual has the right level of FT3 and FT4 for them. T4, T4/T3, NDT and T3-Only (when needed) all have to be available as options from our doctors. Current thyroid treatment is failing patients - it does not take into account research that clearly contradicts current practices.