Sweetman, Eiren, Tate, Warren P · Methods in molecular biology (Clifton, N.J.) · 2025 · DOI
Researchers developed a new blood test that measures a specific immune protein called PKR in white blood cells to help diagnose ME/CFS. The test looks at whether PKR is in an active or inactive form—people with ME/CFS appear to have different patterns of active PKR compared to healthy people. If this method works well in larger studies, it could provide doctors with a simple, quick way to diagnose ME/CFS instead of waiting months while ruling out other illnesses.
ME/CFS currently lacks an objective diagnostic biomarker, forcing patients through years of exclusionary testing and contributing to diagnostic delays and invalidation. A validated PKR phosphorylation ratio test could accelerate diagnosis, enable earlier intervention, support disease monitoring, and provide biological evidence that ME/CFS is a measurable organic illness.
This study does not prove that PKR phosphorylation is the cause of ME/CFS—only that the ratio differs between patients and controls. The small sample size and methods-development nature mean the test's sensitivity, specificity, and clinical utility remain unestablished and require independent validation. The findings do not indicate whether PKR activation is a primary driver of disease or a secondary consequence of the illness.
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 →
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