Tomas, Cara, Lodge, Tiffany A, Potter, Michelle et al. · Scientific reports · 2019 · DOI
This study tested a blood test called the Mitochondrial Energy Score (MES) that is marketed to diagnose ME/CFS by measuring how well cells produce energy. Researchers repeated the test in both ME/CFS patients and healthy people and found no difference between the two groups. They also discovered that waiting even 24 hours before processing blood samples changed the test results significantly, suggesting the test is not reliable enough to use for diagnosis.
Many ME/CFS patients have explored the MES test as a potential diagnostic tool, but this study provides important evidence that it should not be relied upon for diagnosis. Understanding which biomarker tests are genuinely reliable versus those with methodological limitations is crucial for patients making healthcare decisions and for researchers pursuing valid diagnostic approaches.
This study does not prove that mitochondrial dysfunction does not occur in ME/CFS—only that this particular test cannot reliably measure it. It also does not establish whether the Myhill group's original findings were fraudulent or merely methodologically flawed due to uncontrolled sample processing variables.
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
Tomas, Cara, Lodge, Tiffany A, Potter, Michelle, Elson, Joanna L, Newton, Julia L, & Morten, Karl J (2019). Assessing cellular energy dysfunction in CFS/ME using a commercially available laboratory test.. Scientific reports. https://doi.org/10.1038/s41598-019-47966-z
BibTeX
@article{mecfsatlas-tomas-2019-assessing-cellular,
author = {Tomas, Cara and Lodge, Tiffany A and Potter, Michelle and Elson, Joanna L and Newton, Julia L and Morten, Karl J},
title = {Assessing cellular energy dysfunction in CFS/ME using a commercially available laboratory test.},
journal = {Scientific reports},
year = {2019},
doi = {10.1038/s41598-019-47966-z},
note = {PubMed: 31391529},
url = {https://www.mecfsatlas.com/evidence/tomas-2019-assessing-cellular},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/tomas-2019-assessing-cellular
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