Nacul, Luis, de Barros, Barbara, Kingdon, Caroline C et al. · Diagnostics (Basel, Switzerland) · 2019 · DOI
Researchers tested blood samples from 272 people with ME/CFS and 136 healthy people to look for measurable differences that might help diagnose the condition. They found that people with severe ME/CFS had notably lower levels of an enzyme called creatine kinase (CK) in their blood compared to healthy people and those with milder ME/CFS. This is the first study to report this pattern, suggesting that CK levels might be useful for identifying who has the most severe form of the disease.
ME/CFS currently lacks a specific diagnostic biomarker, making clinical diagnosis challenging and delayed. Identifying that severe ME/CFS is associated with distinctly lower CK levels offers a potential objective measure to distinguish disease severity and support diagnosis, which could accelerate diagnosis and enable better disease stratification in future research and clinical settings.
This study does not prove that low CK causes severe ME/CFS or that it can be used alone as a diagnostic test for the condition. The cross-sectional design captures only one moment in time and cannot establish whether CK levels change over the disease course or predict outcomes. Further validation in prospective studies and diverse populations is needed before clinical implementation.
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
Nacul, Luis, de Barros, Barbara, Kingdon, Caroline C, Cliff, Jacqueline M, Clark, Taane G, Mudie, Kathleen, et al. (2019). Evidence of Clinical Pathology Abnormalities in People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) from an Analytic Cross-Sectional Study.. Diagnostics (Basel, Switzerland). https://doi.org/10.3390/diagnostics9020041
BibTeX
@article{mecfsatlas-nacul-2019-evidence-clinical,
author = {Nacul, Luis and de Barros, Barbara and Kingdon, Caroline C and Cliff, Jacqueline M and Clark, Taane G and Mudie, Kathleen and Dockrell, Hazel M and Lacerda, Eliana M},
title = {Evidence of Clinical Pathology Abnormalities in People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) from an Analytic Cross-Sectional Study.},
journal = {Diagnostics (Basel, Switzerland)},
year = {2019},
doi = {10.3390/diagnostics9020041},
note = {PubMed: 30974900},
url = {https://www.mecfsatlas.com/evidence/nacul-2019-evidence-clinical},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/nacul-2019-evidence-clinical
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