“Low T3 Syndrome”, “Euthyroid Sick Syndrome”, or “Intracellular Hypothyroidism”
In November 2021, I received a paper, by Begoña Ruiz-Núñez, Rabab Tarasse, Emar F Vogelaar, D A Janneke Dijck-Brouwer, Frits A J Muskiet PMID: 29615976, PMCID: PMC5869352, DOI:10.3389/fendo.2018.00097, Front Endocrinol (Lausanne), 2018 Mar 20;9:97. doi: 10.3389/fendo.2018.00097. 2018.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869352/
The paper is entitled “chronic fatigue syndrome: a case control study”: to my amazement, the authors had included reverse T3, the only incontrovertible marker for Intracellular Hypothyroidism, in their report.
ABSTRACT (paraphrased, for brevity and clarity)
Chronic fatigue syndrome (CFS) is a heterogeneous disease, of unknown cause.
CFS symptoms resemble a hypothyroid state, secondary to chronic inflammation.
We studied 98 CFS patients and 99 age- and sex-matched controls.
We measured parameters of thyroid function, (metabolic) inflammation, gut wall integrity and nutrients influencing thyroid function and/or inflammation.
Remarkably, CFS patients exhibited:
Similar TSH,
Lower free T3 (FT3),
Lower total thyroxine (TT4),
Lower total T3 (TT3),
Lower %TT3 (4.7%),
Lower activity of deiodinases,
Lower secretory capacity of the thyroid gland (14.9%) and
Lower 24-h urinary iodine (27.6%).
The % of reverse T3 (rT3) was higher (13.3%), among the patients and FT3 below the normal range, consistent with the “low T3 syndrome,” was found in 16/98 Chronic Fatigue Syndrome patients, Vs. 7/99 controls.
We also found evidence of low-grade metabolic inflammation (ferritin & HDL-C).
FT3, TT3, TT4, and rT3 correlated positively with HS CRP in CFS patients and controls. TT3 and TT4 were positively related to HS CRP, in controls.
Low T3 and the shift from T3 to rT3 may reflect depressed tissue T3 levels.
The findings in chronic fatigue syndrome patients agree with studies suggesting a hypometabolic state.
They resemble the “non-thyroidal illness syndrome” and “low T3 syndrome” experienced by a subgroup of hypothyroid patients receiving T4 monotherapy.
Our study needs confirmation by others: trials with,T3 and iodide supplements might be indicated.
Keywords: chronic fatigue syndrome, thyroid, “low T3 syndrome”, triiodothyronine, reverse triiodothyronine, urinary iodine, inflammation, high-sensitive C-reactive protein
My COMMENT ON THIS ARTICLE:
This is a truly excellent paper.
It agrees with me, that Chronic Fatigue Syndrome symptoms resemble a hypothyroid state, or at least that there is a relationship between CFS and “Functional (Intracellular) Hypothyroidism“.
It raises the obvious question: can Chronic Fatigue Syndrome be treated? …..
The answer is “yes”! see below.
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