Nater, Urs M, Maloney, Elizabeth, Boneva, Roumiana S et al. · The Journal of clinical endocrinology and metabolism · 2008 · DOI
This study looked at cortisol, a hormone released by the body in the morning to help us wake up and manage stress. Researchers compared cortisol levels in people with ME/CFS to healthy people and found that ME/CFS patients, especially women, had lower morning cortisol levels than expected. This suggests the hormone system that controls cortisol may not be working normally in ME/CFS.
HPA axis dysfunction is a proposed biological mechanism in ME/CFS, and identifying measurable biomarkers like attenuated cortisol could help with diagnosis and understanding disease pathophysiology. The finding of sex-specific differences suggests that men and women with ME/CFS may have distinct biological profiles, potentially explaining why women are diagnosed more frequently and may help guide personalized treatment approaches.
This study does not prove that low cortisol causes ME/CFS—it shows an association only. The cross-sectional design cannot establish whether cortisol dysregulation precedes CFS onset or develops as a consequence of illness. The findings also cannot explain the mechanisms underlying the sex difference or determine whether cortisol abnormalities are universal across all ME/CFS patients.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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