Korszun, A, Young, E A, Engleberg, N C et al. · The Journal of rheumatology · 2000
Researchers tested whether women with fibromyalgia (FM) and chronic fatigue syndrome (CFS) have imbalances in hormones related to reproduction and the menstrual cycle. They collected blood samples every 10 minutes over 12 hours from women with FM, women with CFS, and healthy controls during the first part of the menstrual cycle. They found no significant differences in hormone levels or patterns between the patient groups and healthy women.
Hormonal abnormalities have been proposed as a mechanism in ME/CFS and FM, particularly because these conditions affect more women than men. This systematic investigation of reproductive hormone function helps clarify whether HPG axis dysfunction is a central feature of these diseases, which could inform treatment approaches.
This study does not prove that hormonal abnormalities play no role in FM/CFS pathophysiology—it only indicates that HPG axis function appears normal during the follicular phase in this specific small sample. The study cannot exclude abnormalities in other hormonal axes, other phases of the menstrual cycle, or in men with these conditions. Negative findings in a small study do not rule out subtle or condition-relevant hormonal perturbations.
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
Korszun, A, Young, E A, Engleberg, N C, Masterson, L, Dawson, E C, Spindler, K, et al. (2000). Follicular phase hypothalamic-pituitary-gonadal axis function in women with fibromyalgia and chronic fatigue syndrome.. The Journal of rheumatology. https://pubmed.ncbi.nlm.nih.gov/10852283/
BibTeX
@article{mecfsatlas-korszun-2000-follicular-phase,
author = {Korszun, A and Young, E A and Engleberg, N C and Masterson, L and Dawson, E C and Spindler, K and McClure, L A and Brown, M B and Crofford, L J},
title = {Follicular phase hypothalamic-pituitary-gonadal axis function in women with fibromyalgia and chronic fatigue syndrome.},
journal = {The Journal of rheumatology},
year = {2000},
note = {PubMed: 10852283},
url = {https://www.mecfsatlas.com/evidence/korszun-2000-follicular-phase},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/korszun-2000-follicular-phase
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