There is controversy regarding the incidence and significance of hypothalamic-pituitaryadrenal (HPA) axis dysfunction in Chronic Fatigue Syndrome (CFS) and Fibromyalgia (FM). Studies that utilize central acting stimulation tests, including CRH, IST, d-fenfluramine, ipsapirone, IL-6 and metyrapone testing, have demonstrated that HPA axis dysfunction of central origin is present in a majority of these patients.
However, ACTH stimulation tests and baseline cortisol testing lack the sensitivity to detect this central dysfunction and have resulted in controversy and confusion regarding the incidence of HPA axis dysfunction in these conditions and the appropriateness of treatment.
While both CFS and FM patients are shown to have central HPA dysfunction, the dysfunction in CFS appears to be at the pituitaryhypothalamic level while the dysfunction in FM is more related to dysfunction at the hypothalamic and supra-hypothalamic levels.
Because treatment with low physiologic doses of cortisol (< 15 mg) has been shown to be safe and effective and routine dynamic ACTH testing does not appear to have significant diagnostic sensitivity, it is reasonable to give a therapeutic trial of physiologic doses of cortisol to the majority of patients with CFS and FM, especially to those who have symptoms that are consistent with adrenal dysfunction, have low blood pressure, or have baseline cortisol levels in the low or low-normal range.
Source: Journal of Chronic Fatigue Syndrome, vol 14 #3, 2007. (Prepublication) DOI: 10.1300/ , by Holtforf K.