In his review article about fibromyalgia syndrome (FM), Goldenberg1 highlights the similarity between FM and chronic fatigue syndrome (CFS) and goes as far as stating that "these syndromes overlap so extensively that it may be concluded that each represents different presentations of the same general condition." This is unlikely to be the case because, as Crofford et al2 pointed out, "comparison of hypothalamic-pituitary-adrenal axis function in FM with patients with CFS reveals differences despite the significant clinical overlap between these patients." Other recently observed differences, according to Evengard et al,3 "further support that FM and CFS are different disorders in spite of overlapping symptomatology."
Baschetti R. Fibromyalgia, Chronic Fatigue Syndrome, and Addison Disease. Arch Intern Med. 1999;159(20):2481. doi: