In a considerable number of chronic fatigue syndrome patients, researchers have observed the presence of autoantibodies to the selenium transporter Selenoprotein P. These autoantibodies disturb the normal transport of selenium to the tissues in the body. They cause lower than normal levels of the antioxidant selenoenzyme glutathione peroxidase and lower than normal levels of deiodinase enzyme activity [Sun 2023].
Note: Autoantibodies are antibodies produced by the immune system and directed against the individual’s own proteins, in this case against selenoprotein P proteins. In an earlier study, researchers have identified autoantibodies to selenoprotein P in patients with Hashimoto’s thyroiditis, in which case the autoantibodies also impair selenium transport and selenoprotein expression [Sun 2021].
Note: Deiodinase enzymes are enzymes involved in the activation and deactivation of thyroid hormones.
The Selenoprotein P and Chronic Fatigue Syndrome Study
The symptoms of chronic fatigue syndrome are similar to the symptoms of hypothyroidism, e.g., to Hashimoto’s thyroiditis. The symptoms include mental and physical fatigue, poor sleep, depression, and anxiety. The difference is that chronic fatigue syndrome patients do not experience the elevated thyrotropin (TSH) and low thyroxine (T4) levels that are observed in patients with hypothyroidism [Sun 2023].
In the present study, the researchers compared selenium status in chronic fatigue syndrome patients (n=167) to selenium status in healthy controls (n=545). The study included two additional small groups [Sun 2023]:
- patients with fibromyalgia (n=39)
- patients with post-COVID condition (n=24)
The researchers measured the following serum/plasma selenium biomarkers:
- total selenium
- glutathione peroxidase
- selenoprotein P
The three biomarkers of selenium status showed linear correlations without reaching saturation levels, which indicated a condition of selenium deficiency in the chronic fatigue syndrome patients. The TSH and total T4 levels were, however, within normal ranges. Relative total T3 was low, and reverse T3, a metabolite of T4, was elevated in the chronic fatigue syndrome patients [Sun 2023].
The prevalence of the selenoprotein P autoantibodies in the chronic fatigue syndrome patients was between 10 and 15% whereas the corresponding prevalence in healthy controls was 2% or less [Sun 2023].
In the chronic fatigue syndrome patients with the selenoprotein P autoantibodies, the researchers observed differences from healthy controls [Sun 2023]:
- lack of correlation between total selenium levels and glutathione peroxidase-3 activity levels
- disturbed thyroid hormone parameters: low deiodinase activity and particularly low urinary iodine
These differences suggest that there is an impairment of selenium transport in chronic fatigue syndrome patients with the selenoprotein P autoantibodies. The differences also suggest that the selenoprotein P autoantibodies affect thyroid hormone deiodination and iodine excretion [Sun 2023].
Conclusions: Selenoprotein P Autoimmunity in Chronic Fatigue Syndrome patients
- The prevalence of selenoprotein P autoimmunity in patients with chronic fatigue syndrome is relatively high.
- The impaired selenium transport caused by the selenoprotein P autoimmunity seems to be associated with target cell selenium deficiency.
- The impaired selenium transport is associated with low glutathione peroxidase-3 activity, with suppressed thyroid hormone metabolism, and with low urinary iodine levels.
- The researchers suggest personalized treatment of chronic fatigue syndrome patients with selenoprotein P autoimmunity.
- Personalized treatment for chronic fatigue syndrome patients with diagnosed selenoprotein P autoimmunity would consist of selenium supplementation and T3 substitution to correct the deficits and support convalescence [Sun 2023].
Sun Q, Mehl S, Renko K, Seemann P, Görlich CL, Hackler J, Minich WB, Kahaly GJ, Schomburg L. Natural Autoimmunity to Selenoprotein P Impairs Selenium Transport in Hashimoto’s Thyroiditis. Int J Mol Sci. 2021 Dec 3;22(23):13088.
Sun Q, Oltra E, Dijck-Brouwer DAJ, Chillon TS, Seemann P, Asaad S, Demircan K, Espejo-Oltra JA, Sánchez-Fito T, Martín-Martínez E, Minich WB, Muskiet FAJ, Schomburg L. Autoantibodies to selenoprotein P in chronic fatigue syndrome suggest selenium transport impairment and acquired resistance to thyroid hormone. Redox Biol. 2023 Sep;65:102796.
The information presented in this review article is not intended as medical advice and should not be used as such.
15 August 2023