Cleare, A J, Blair, D, Chambers, S et al. · The American journal of psychiatry · 2001 · DOI
This study measured a stress hormone called cortisol in the urine of people with ME/CFS and compared it to healthy controls. The researchers found that people with ME/CFS had lower cortisol levels than expected. This difference was consistent across the patient group and wasn't explained by depression, medications, sleep problems, or disability levels.
This finding suggests that ME/CFS may involve dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, a system crucial for stress response and immune regulation. Identifying biological markers like abnormal cortisol levels could help validate ME/CFS as a physiological condition and potentially guide future treatment approaches targeting endocrine dysfunction.
This study does not prove that low cortisol causes ME/CFS or is the primary mechanism of the illness. The cross-sectional design captures one moment in time and cannot establish whether cortisol abnormalities develop before, during, or as a consequence of illness. It does not identify whether hypocortisolism is a direct feature of ME/CFS pathology or secondary to other biological processes.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Cleare, A J, Blair, D, Chambers, S, & Wessely, S (2001). Urinary free cortisol in chronic fatigue syndrome.. The American journal of psychiatry. https://doi.org/10.1176/appi.ajp.158.4.641
BibTeX
@article{mecfsatlas-cleare-2001-urinary-free,
author = {Cleare, A J and Blair, D and Chambers, S and Wessely, S},
title = {Urinary free cortisol in chronic fatigue syndrome.},
journal = {The American journal of psychiatry},
year = {2001},
doi = {10.1176/appi.ajp.158.4.641},
note = {PubMed: 11282703},
url = {https://www.mecfsatlas.com/evidence/cleare-2001-urinary-free},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/cleare-2001-urinary-free
Contribute
Private, reviewed by a human. Not a public comment thread.