Moorkens, G, Berwaerts, J, Wynants, H et al. · Clinical endocrinology · 2000 · DOI
This study examined hormone levels in 73 people with ME/CFS compared to 21 healthy people. Researchers found that people with ME/CFS had lower growth hormone (GH) levels, especially at night and when their body was stressed by low blood sugar. They also had higher levels of prolactin and thyroid-stimulating hormone (TSH), suggesting their brain chemistry may be imbalanced. These hormone changes were associated with increased belly fat in ME/CFS patients.
This study provides quantitative evidence of neuroendocrine dysfunction in ME/CFS, particularly GH dysregulation, which may explain the fatigue, exercise intolerance, and metabolic changes patients experience. The findings support biological abnormalities in ME/CFS and suggest that the condition involves measurable alterations in brain-pituitary signaling rather than being purely psychological.
This study does not prove that GH deficiency causes ME/CFS symptoms or that GH replacement would benefit patients. The observation of normal IGF-I levels (GH's main functional mediator) raises questions about the clinical significance of the observed GH reduction. Correlation between hormone changes and visceral fat does not establish causation, and cross-sectional design prevents determination of whether hormonal changes precede symptom onset.
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
Moorkens, G, Berwaerts, J, Wynants, H, & Abs, R (2000). Characterization of pituitary function with emphasis on GH secretion in the chronic fatigue syndrome.. Clinical endocrinology. https://doi.org/10.1046/j.1365-2265.2000.01049.x
BibTeX
@article{mecfsatlas-moorkens-2000-characterization-pituitary,
author = {Moorkens, G and Berwaerts, J and Wynants, H and Abs, R},
title = {Characterization of pituitary function with emphasis on GH secretion in the chronic fatigue syndrome.},
journal = {Clinical endocrinology},
year = {2000},
doi = {10.1046/j.1365-2265.2000.01049.x},
note = {PubMed: 10931086},
url = {https://www.mecfsatlas.com/evidence/moorkens-2000-characterization-pituitary},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/moorkens-2000-characterization-pituitary
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