24h urinary cortisol excretion was sig. lower in a series of CFS patients than in a control gorup of 64 pts without CFS in one cohort study; no diff. in cortisol levels among CFS pts were seen between those with sig. psychiatric history and those without (Am. J. Psych. 158:641, 2001--JW)

32 pts with CFS but w/o comorbid psychiatric disorder randomized to low-dose Hydrocortisone vs. placebo showed sig. greater imrpovements in self-rated fatigue and disability (Lancet 353:455, 1999--UW Pharm Letter); however, other randomized trials have not shown a benefit.

Presence of low-molecular-weight "2-A proteins" (proteins which bind to ribonuclease L and degrade viral RNA) was sig. greater in pts with CFS than in controls in one study (Am. J. Med. 108:99, 2000--JW)

May be associated with murine leukemia virus-related viruses