E3 PreliminaryModerate confidencePEM not requiredMechanisticPeer-reviewedMachine draft
Standard · 3 min
Basal circadian and pulsatile ACTH and cortisol secretion in patients with fibromyalgia and/or chronic fatigue syndrome.
Crofford, Leslie J, Young, Elizabeth A, Engleberg, N Cary et al. · Brain, behavior, and immunity · 2004 · DOI
Quick Summary
This study measured stress hormones (ACTH and cortisol) throughout a 24-hour period in patients with fibromyalgia, chronic fatigue syndrome, or both, compared to healthy controls. Researchers found that fibromyalgia patients had abnormal cortisol patterns—particularly elevated levels in the evening and delayed decline throughout the day—suggesting their stress hormone system doesn't recover properly. Chronic fatigue syndrome patients showed some differences but they were smaller and not statistically significant.
Why It Matters
HPA axis dysfunction is a proposed biological mechanism in both ME/CFS and fibromyalgia. This study provides objective evidence of abnormal stress hormone patterns, particularly in fibromyalgia, which could help explain fatigue, pain, and immune dysregulation. Understanding whether HPA axis changes are disease-causing or secondary could inform future treatments targeting the stress response system.
Observed Findings
Fibromyalgia patients showed significant delay in the rate of cortisol decline from peak to trough levels (P<.01).
Elevated cortisol in late evening quiescent period was present in approximately 50% of FMS patients compared to controls.
CFS patients showed numerically lower overnight cortisol levels compared to controls, but the difference was not statistically significant.
ACTH and cortisol pulsatility patterns did not show statistically significant differences between patient and control groups.
Evaluable samples were obtained for ACTH from 36 subject pairs and cortisol from 37 subject pairs.
Inferred Conclusions
The circadian architecture of HPA axis hormones differs between FMS and CFS patients compared to matched controls, with distinct patterns for each condition.
Fibromyalgia is associated with loss of HPA axis resiliency, particularly evident in impaired cortisol decline and evening elevation.
CFS may involve different HPA axis abnormalities than FMS, though the specific pattern in this study did not reach statistical significance.
Pulsatile hormone secretion, as opposed to circadian rhythm architecture, may not be the primary HPA axis abnormality in these conditions.
Remaining Questions
What This Study Does Not Prove
This study does not establish causation—abnormal cortisol patterns could be a consequence of chronic illness rather than a cause. The findings in CFS patients were not statistically significant, so no firm conclusions about HPA axis dysfunction in CFS alone can be drawn from this data. The study excluded patients with psychiatric disorders, so findings may not apply to patients with comorbid depression or anxiety.
Tags
Symptom:PainFatigue
Biomarker:Blood Biomarker
Method Flag:PEM Not DefinedSmall SampleMixed Cohort
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 →
Do the observed cortisol abnormalities in fibromyalgia directly contribute to symptom generation, or are they secondary to chronic pain and illness?
Why do FMS and CFS+FMS show more pronounced HPA axis abnormalities than CFS alone, and what explains the biological differences between these conditions?
Do these HPA axis alterations persist over time, or do they fluctuate with symptom severity and disease progression?
Could therapeutic interventions targeting HPA axis function (e.g., low-dose corticosteroids or stress management) improve outcomes in these patient populations?