CHRONIC FATIGUE SYNDROME
a.k.a. "Low T3 Syndrome", a.k.a. "Intracellular Hypothyroidism" – symptoms, diagnosis and treatment.
In November 2021 I received a paper, entitled “Chronic Fatigue Syndrome: a case control study”, 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/.
Please see the abstract of this important article, followed by my opinion, below.
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, measuring parameters of thyroid function, (metabolic) inflammation, gut wall integrity and nutrients influencing thyroid function and/or inflammation.
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. 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 HSCRP in both CFS patients and controls.
TT3 and TT4 were positively related to HSCRP in controls.
Low T3, and the shift from T3 to rT3, may reflect more depressed tissue T3 levels.
The findings in chronic fatigue syndrome patients agree with studies suggesting a hypometabolic state. They resemble “non-thyroidal illness syndrome”, a.k.a. “low T3 syndrome” (I prefer to call it “intracellular hypothyroidism”), 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
