E0 ConsensusModerate confidencePEM not requiredSystematic-ReviewPeer-reviewedReviewed
Standard · 3 min
Hypothalamic-pituitary-adrenal axis dysfunction in chronic fatigue syndrome.
Papadopoulos, Andrew S, Cleare, Anthony J · Nature reviews. Endocrinology · 2011 · DOI
Quick Summary
ME/CFS patients often have abnormal levels of cortisol, a stress hormone produced by the body. This review found that people with ME/CFS tend to have lower cortisol levels than healthy people, with less variation throughout the day and a weaker response to stress. These hormone changes are linked to worse symptoms and disability, and treatments like cognitive behavioral therapy may help restore more normal cortisol levels.
Why It Matters
HPA axis dysfunction appears to be a consistent biological feature of ME/CFS that correlates with disease severity and treatment response, potentially offering a measurable biomarker and therapeutic target. Understanding the multifactorial causes of these hormonal changes—including modifiable factors like activity level and depression—may inform personalized treatment approaches for this poorly understood condition.
Observed Findings
ME/CFS patients have mild hypocortisolism (low cortisol levels) compared to healthy controls.
Diurnal cortisol variation (normal daily rhythm) is attenuated in ME/CFS.
ME/CFS patients exhibit blunted HPA axis responsiveness to stressors.
Women with ME/CFS are more likely to have reduced cortisol levels than men.
Inferred Conclusions
HPA axis changes in ME/CFS are clinically relevant and associated with worse symptoms, disability, and poorer treatment outcomes.
Multiple factors—low activity levels, depression, early-life stress, and psychotropic medications—interact to moderate HPA axis dysfunction.
Cognitive behavioral therapy is a potentially effective first-line treatment for HPA axis dysfunction in ME/CFS, superior to steroid replacement.
Remaining Questions
What is the primary cause of HPA axis dysfunction in ME/CFS—is it a primary neuroendocrine disorder or secondary to other disease mechanisms?
Does correcting cortisol abnormalities through treatment lead to clinical improvement in ME/CFS symptoms?
What This Study Does Not Prove
This review does not prove that HPA axis dysfunction causes ME/CFS, only that it is associated with the condition; the direction of causality remains unclear. It does not establish which HPA abnormalities are primary versus secondary consequences of illness-related factors, nor does it demonstrate that correcting cortisol levels will resolve ME/CFS symptoms.
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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