Attenuated morning salivary cortisol concentrations in a population-based study of persons with chronic fatigue syndrome and well controls. — ME/CFS Atlas
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Attenuated morning salivary cortisol concentrations in a population-based study of persons with chronic fatigue syndrome and well controls.
Nater, Urs M, Maloney, Elizabeth, Boneva, Roumiana S et al. · The Journal of clinical endocrinology and metabolism · 2008 · DOI
Quick Summary
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.
Why It Matters
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.
Observed Findings
CFS group showed significantly attenuated morning cortisol concentrations compared to controls across the measurement period
Women with CFS exhibited markedly suppressed cortisol profiles relative to healthy women
Men with CFS showed cortisol profiles similar to male controls, indicating no significant sex-specific difference in males
A significant interaction effect was observed between group (CFS vs. control) and time/cortisol profile
The study was conducted in a medication-free population, reducing confounding from pharmaceutical effects
Inferred Conclusions
Morning salivary cortisol responses are attenuated in persons with CFS, suggesting HPA axis dysregulation
This HPA axis dysregulation appears to be sex-specific, occurring primarily in women with CFS
Hypocortisolism in women may represent a biological risk factor contributing to the female predominance of CFS
Sex differences in HPA axis function warrant investigation as a component of ME/CFS pathophysiology
Remaining Questions
Why does cortisol dysregulation occur primarily in women with CFS but not in men?
What This Study Does Not Prove
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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