Azimi, Ghazaleh, Elremaly, Wesam, Elbakry, Mohamed et al. · International journal of molecular sciences · 2025 · DOI
This study measured a protein called FGF-21 in the blood of people with ME/CFS, fibromyalgia, and both conditions combined, then compared how their symptoms and thinking abilities differed based on their FGF-21 levels. The researchers found that FGF-21 levels—not just the diagnosis alone—were better at predicting which symptoms and cognitive problems each person would experience. This suggests FGF-21 could become a useful blood test to help doctors understand and treat these conditions more precisely.
Currently, ME/CFS and fibromyalgia lack objective diagnostic biomarkers, making clinical subtypes and treatment selection difficult. If FGF-21 can reliably identify patient subtypes with different symptom profiles and treatment needs, it could enable precision medicine approaches and help develop targeted therapies. This work addresses a critical gap in understanding biological heterogeneity within these overlapping syndromes.
This study does not prove that FGF-21 causes the observed symptoms—it only shows association at one time point. The cross-sectional design cannot establish causation or determine whether FGF-21 changes drive symptoms or respond to them. FGF-21 may also be a marker of other underlying biological processes rather than the direct mechanism of disease.
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
Azimi, Ghazaleh, Elremaly, Wesam, Elbakry, Mohamed, Franco, Anita, Godbout, Christian, & Moreau, Alain (2025). Circulating FGF-21 as a Disease-Modifying Factor Associated with Distinct Symptoms and Cognitive Profiles in Myalgic Encephalomyelitis and Fibromyalgia.. International journal of molecular sciences. https://doi.org/10.3390/ijms26167670
BibTeX
@article{mecfsatlas-azimi-2025-circulating-fgf,
author = {Azimi, Ghazaleh and Elremaly, Wesam and Elbakry, Mohamed and Franco, Anita and Godbout, Christian and Moreau, Alain},
title = {Circulating FGF-21 as a Disease-Modifying Factor Associated with Distinct Symptoms and Cognitive Profiles in Myalgic Encephalomyelitis and Fibromyalgia.},
journal = {International journal of molecular sciences},
year = {2025},
doi = {10.3390/ijms26167670},
note = {PubMed: 40868993},
url = {https://www.mecfsatlas.com/evidence/azimi-2025-circulating-fgf},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/azimi-2025-circulating-fgf
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