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The CFS/ME-Hypothyroidism Connection

Written by: Mary Shomon


Dr. Teitelbaum believes that an underlying hypothalamic-pituitary dysfunction – potentially caused by viral damage -- could be common to many cases of both CFS and hypothyroidism. His conclusion that CFS and hypothyroidism are connected is borne out by a number of studies that have shown various links between underlying infections common to both CFS patients, and patients with subclinical or overt hypothyroidism. For example, several studies have found higher-than-normal incidence of human herpesvirus 6 (HHV-6) infection and Epstein Barr Virus (EBV) in both CFS and patients with Hashimoto’s thyroiditis, the autoimmune disease that causes hypothyroidism.

One of the most groundbreaking studies was released in 2018. Titled “Higher Prevalence of “ Low T3 Syndrome” in Patients With Chronic Fatigue Syndrome: A Case–Control Study, the study was published in the journal Frontiers in Endocrinology. The researchers reported that CFS, like hypothyroidism, is characterized by low levels of most – but not all – thyroid hormones.

Researchers found that most CFS patients had low or low-normal levels of the two key thyroid hormones -- triiodothyronine (T3) and thyroxine (T4). A significant number of the CFS patients also had levels of free T3 – the active and available thyroid hormone that helps oxygen and energy reach cells – that were below the reference range. The CFS patients also tended to have lower iodine levels and higher Reverse T3 levels. Surprisingly, despite all these markers for hypothyroidism, the CFS patients had normal levels of thyroid stimulating hormone (TSH). This meant that conventional guidelines would exclude a diagnosis of hypothyroidism.

Instead, according to the researchers, “the low T3 levels found in CFS patients coupled with this switchover to Reverse T3 could mean that T3 levels are severely reduced in tissue.” To that end, the study authors concluded that CFS could be characterized as a “nonthyroidal illness syndrome (NTIS)” or “low T3 syndrome.”

According to the researchers, while more studies are needed to confirm their findings, trials of treatment with T3 medication and iodine supplements might be indicated in CFS patients.

Interestingly, the researchers also found that the metabolic profile of the CFS patients closely resembled those of hypothyroid patients on levothyroxine (T4) treatment who had persistent and unresolved symptoms, including fatigue. This led the researchers to conclude that T3 treatment may be effective not only in CFS patients, but also in hypothyroid patients with continued symptoms on levothyroxine.

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