Problems with the thyroid – the “gas pedal of the body”, as Dr. Teitelbaum calls it – seem to make sense given the fatigue, exercise and other problems found in ME/CFS and FM. Assessing and treating the thyroid, though, is one area where the practices of chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) doctors may distinctly diverge from other doctors.
Standard thyroid tests are often negative in ME/CFS and FM but Dr. Bateman has stated that about a third of her ME/CFS patients are hypothyroid. Dr Holtorf – who has published on thyroid issues – believes the standard TSH tests are looking in the wrong place.
Those tests assess the pituitary’s role in triggering thyroid hormone production. Holtorf asserts, though, that pituitary thyroid hormone levels often do not reflect the profound thyroid hormone reductions in other parts of the body in many people with ME/CFS and FM.
T4 – the hormone produced by the thyroid – is not the most active form of thyroid hormone. It’s only when T4 is broken down by non-thyroid tissues, such as the liver, that T3 – the biologically active form of thyroid hormone – is produced.
Holtorf believes that thyroid tests that more directly measure thyroid levels (free T3) or thyroid hormone inhibitors (reverse T3; free T3/reverse T3) as well as other metabolic and inflammatory tests (basal metabolic rate, SHBG, leptin, ferritin, tendon reflexes) should be incorporated into standard ME/CFS and FM testing.
Last year, a large (n=197) Dutch study explored the thyroid question in ME/CFS in greater depth than ever before, and in doing so, may have uncovered a new thyroid illness subset.
Hypothesizing that the “subclinical hypothyroidism” (based on normal TSH levels) found in ME/CFS is caused by low-grade inflammation, these researchers dug deeper than most. Not only did they examine a full array of thyroid measures, but they also assessed traditional markers of inflammation, metabolic inflammation (insulin resistance-mediated, de novo lipogenesis (DNL), and HDL-cholesterol (HDL-C). (Metabolic inflammation refers to conditions where metabolic and inflammatory pathways contribute to atherosclerosis, insulin resistance (IR) and type 2 diabetes.)
Plus, thinking of the leaky gut/inflammation question, they assessed gut wall integrity and the status of nutrients that can influence thyroid function (iodine and selenium) and inflammation (fish oil fatty acids, Vit. D, kyrnurenine, tryptophan, etc.).
With 99 people with ME/CFS and 98 healthy controls, the study appeared quite robust.
The results bore Dr. Holtorf’s conclusions out that TSH tests are insufficient to assess thyroid functioning in chronic fatigue syndrome and fibromyalgia.
These Dutch and Spanish researchers found that TSH levels were indeed similar between ME/CFS patients and healthy controls, but virtually every other thyroid measure was significantly lower in the ME/CFS group (free triiodothyronine (FT3) (difference of medians 0.1%), total thyroxine (TT4) (11.9%), total triiodothyronine (TT3) (12.5%), %TT3 (4.7%), sum activity of deiodinases (14.4%), secretory capacity of the thyroid gland (14.9%), and 24-h urinary iodine (27.6%). Plus, higher percentages of reverse T3 (rT3) (13.3%) suggested that increased levels of thyroid inhibition may be present in ME/CFS.
The authors called the lowered 24-h urine iodine output of ME/CFS patients “remarkable” (which may simply mean “notable”). Both the ME/CFS group and the healthy controls also had about half the optimum omega-3 indexes believed needed to protect against cardiovascular and neuropsychiatric diseases.
Documenting evidence of widespread thyroid problems not picked up by standard TSH tests was progress indeed, but the finding that really stood out concerned the 16% of ME/CFS patients who fit the criteria for “low T3 syndrome”. (Seven percent of the healthy controls did too.)
A fairly large Dutch study found evidence of low thyroid functioning in ME/CFS. The study needs to be replicated, but about 15% of the ME/CFS group met the criteria for Non-Thyroidal Illness Syndrome (NTIS) which occurs in starvation, sepsis and probably other serious illnesses. While most people with ME/CFS did not meet the criteria for NTIS, the overall findings – normal TSH levels, increased reverse T3, and reductions in a variety of thyroid tests – suggest the group as a whole trended in the direction of NTIS.
The findings may call for the use of T3 instead of T4 for some people with ME/CFS/FM. While studies assessing the effectiveness of T3 are lacking, both Leslie DeGroot, a prominent endocrinologist, and Dr. Kent Holtorf, an ME/CFS/FM specialist, support using T3 (in Dr. Holtorf’s case, compounded T3) instead of the usual T4 preparation (such as Synthroid) in patients with NTIS (DeGroot) or ME/CFS/FM (Holtorf).