Symptoms of chronic fatigue syndrome (CFS), such as weakness, fatigue, and depression, may be associated with low levels of thyroid hormone, according to a small study published in Frontiers in Endocrinology.
Researchers at the University Medical Center Groningen, The Netherlands, compared thyroid function and inflammation markers in 98 people with chronic fatigue syndrome and 99 healthy controls. They found that CFS patients had lower blood levels of certain thyroid hormones, including triiodothyronine (T3) and thyroxine (T4); normal levels of thyroid-stimulating hormone; and higher levels of reverse T3 (rT3).
Chronic fatigue syndrome is primarily diagnosed based on symptoms – which are similar to symptoms of hypothyroidism – and by ruling out underlying medical conditions. The cause of CFS is unknown.