Exploring levels of TSH and FT4 in patients with [CFS], [FM] and healthy controls did not reveal any associations [...], 2024, Skorpen et al.

Exploring levels of TSH and FT4 in patients with chronic fatigue syndrome CFS, fibromyalgia FM and healthy controls did not reveal any associations between fatigue score and level of thyroid hormones
Elias Skorpen; Nora Bugge Pasca; Solveig Klæbo Reitan; Nina Groven

AIMS
The diagnoses of Chronic Fatigue Syndrome (CFS) and Fibromyalgia (FM) are highly associated with fatigue and pain, respectively. Physiologically and clinically an effect of thyroid status on fatigue and pain is expected. There may be clinically relevant differences in thyroid hormone axes though within values of reference in both patients with normal thyroid hormones, or in patients with well-regulated thyroid disease. These potential differences are explored in this study.

MATERIALS AND METHODS
In the present study, female patients with CFS (n = 49) and FM (n = 58) as well as female healthy controls (n = 53) were included. We explored plasma levels of TSH and FT4 between the groups using Kruskall-Wallis, and the relation between fatigue score and levels of TSH and FT4 by means of Spearman’s rho.

RESULTS
There were no group differences between CFS patients, FM patients, and healthy controls in levels of TSH and FT4.

CONCLUSIONS
As one might clinically and physiologically expect an association between thyroid function and fatigue, which may be associated with clinical disorders such as CFS and FM, we suggest future studies to examine the field further by exploring the influence of thyroid receptors and responses of the thyroid hormone cascade.

Link | PDF (Nordic Journal of Psychiatry) [Open Access]

 

Fukuda criteria used for "CFS" patients.

"CFS is a clinical diagnosis of exclusion, where other somatic and psychiatric illnesses must be ruled out as the cause of symptoms. It is characterized by pronounced fatigue and reduced functioning. The condition must have persisted for six months or more. At least four additional symptoms must be present, such as problems concentrating, memory issues, sore throat, tender lymph nodes, muscle pain, joint pain, newly onset headaches, poor sleep quality, and post-activity exhaustion lasting more than 24 hours [Citation4,Citation6]. The prevalence of CFS has been estimated to vary from 0.03% to 2.52% according to the diagnostic criteria employed [Citation7] and is between 1.46% and 2.52% when applying the Fukuda criteria [Citation7]."

 

The paper doesn't mention Free T3 being measured in this research despite T3 being the active thyroid hormone. T4 is a prohormone. Conversion of T4 to T3 occurs in the thyroid and several organs around the body. Symptoms associated with thyroid disease are more likely to be correlated with Free T3 than Free T4. And people who are sick are more likely to have poor conversion than people who are healthy, and so the sick will have lower levels of the active thyroid hormone, T3.

Another problem is that timing of blood collection isn't mentioned. TSH has a circadian rhythm* and is normally higher earlier in the morning than it is in the afternoon. (Insomnia or shift work could alter the timings of this rhythm.)

The problems I've pointed out are common to research involving anything thyroid-related. Some doctors have even been known to tell patients that T3 is a "waste product" of thyroid metabolism rather than being the most important thyroid hormone there is. And doctors also tend to think that TSH is all they need to know about thyroid hormones levels. TSH is not a thyroid hormone, it is a pituitary hormone.

* Free Triiodothyronine Has a Distinct Circadian Rhythm That Is Delayed but Parallels Thyrotropin Levels

Scroll down the page to see the graphs in the above paper.

Edit 1 : When they mention T3 they are relying on measures of it done in other research, they didn't test it in this research.

Edit 2 : I wonder if they excluded people who had had a thyroidectomy or had their thyroids killed off with radioactive iodine (RAI).

 

It's not even an accurate label, since PEM causes (for most people) a fatigue-like symptom, which is different from normal exhaustion. Really, if they want to choose terms, they should ask PWME what terms are suitable.

 

TSH is also affected by other factors. If you have a kynurenine problem, you might produce excess picolinic acid, which elevates MIPS-1alpha, which elevates Trh, which elevates Tsh. I told my endocrinologist that neuroinflammation might cause my slightly elevated Tsh, and he simply got angry with me for questioning his superior knowledge about thyroid hormones (which seemed to be "Elevated Tsh = hypothyroidism, here's your prescription for T4"). Yes it's really quite surprising how simplistic doctor's training is about the thyroid system despite the present state of actual knowledge about it. What year are the textbooks stuck in?

 

Probably about mid 1980s in the UK. That's roughly when the factory which made NDT in the UK was closed and it was removed from the BNF (British National Formulary). It was Levo only from then on.

Even the man who invented the TSH test was appalled by the use his test was put to. He thought it was okay for diagnosis but never imagined it would be used to monitor ongoing treatment.

Before TSH was used as a diagnostic test, high levels of cholesterol was used because it rises in hypothyroidism.