Ter Wolbeek, Maike, van Doornen, Lorenz J P, Coffeng, Luc E et al. · Psychoneuroendocrinology · 2007 · DOI
This study looked at whether girls with severe, ongoing fatigue have different stress hormone (cortisol) levels than girls without fatigue. Researchers tested cortisol levels at different times over a year and found that while fatigued girls reported much worse symptoms overall, their cortisol levels were actually normal and similar to non-fatigued girls. This suggests that severe fatigue in adolescents may not be caused by problems with how the body manages stress hormones.
This study addresses a central hypothesis in ME/CFS research—whether HPA-axis dysfunction explains persistent fatigue. By finding normal cortisol patterns despite severe symptoms, it suggests that fatigue mechanisms may be more complex than simple stress hormone dysregulation, potentially redirecting research attention toward other biological pathways.
This study does not prove that the HPA-axis is not involved in ME/CFS; it only shows that salivary cortisol measurements do not capture potential dysregulation. It does not establish causation for fatigue and does not address whether adolescent fatigue in this sample meets ME/CFS diagnostic criteria. The findings may not generalize to adult CFS populations or other physiological markers of HPA dysfunction.
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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