Hudson, M, Cleare, A J · Clinical endocrinology · 1999 · DOI
This study tested whether people with ME/CFS have lower levels of cortisol (a stress hormone) or weaker adrenal gland responses compared to healthy people. Researchers gave small doses of a hormone called Synacthen to 20 ME/CFS patients and 20 healthy controls, then measured cortisol levels over an hour. They found no significant differences between the two groups, suggesting that reduced adrenal reserve may not explain ME/CFS symptoms.
Many ME/CFS patients and researchers have hypothesized that abnormal stress hormone function contributes to fatigue and other symptoms. This study directly tested whether adrenal glands fail to respond adequately to stimulation, providing evidence against one proposed mechanism of ME/CFS pathophysiology. Understanding which biological systems are or are not dysfunctional helps guide future research and potential treatments.
This study does not prove that HPA axis dysfunction plays no role in ME/CFS—it only shows that adrenal responsiveness to acute Synacthen stimulation is preserved. The authors note that HPA abnormalities in ME/CFS may be driven by other factors (sleep disruption, inactivity, circadian rhythm changes) rather than reduced adrenal capacity. A single negative finding does not rule out more subtle or context-dependent HPA axis alterations.
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
Hudson, M & Cleare, A J (1999). The 1microg short Synacthen test in chronic fatigue syndrome.. Clinical endocrinology. https://doi.org/10.1046/j.1365-2265.1999.00856.x
BibTeX
@article{mecfsatlas-hudson-1999-1microg-short,
author = {Hudson, M and Cleare, A J},
title = {The 1microg short Synacthen test in chronic fatigue syndrome.},
journal = {Clinical endocrinology},
year = {1999},
doi = {10.1046/j.1365-2265.1999.00856.x},
note = {PubMed: 10594524},
url = {https://www.mecfsatlas.com/evidence/hudson-1999-1microg-short},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/hudson-1999-1microg-short
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