Scientists in the UK have reported developing what may be the first blood test capable of diagnosing myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) with about 96% accuracy, sparking hope for patients who often wait years for a clinical diagnosis based on symptoms alone. ME/CFS is a complex, debilitating condition marked by unrelenting fatigue that doesn’t improve with rest as well as post-exertional malaise — a worsening of symptoms after physical or mental activity. Because there’s currently no reliable laboratory test, clinicians typically diagnose ME/CFS only after at least six months of symptoms and by ruling out other conditions, which can delay care and worsen outcomes.
The new research, a proof-of-concept study, identified about 200 biomarkers in blood that form a distinctive biological “signature” in people with severe ME/CFS but not in healthy controls. These biomarkers relate to epigenetic changes — structural alterations in chromosomes that influence gene activity — that may result from environmental factors like infection or stress. Using this signature, the proposed test showed 92% sensitivity (correctly identifying people with ME/CFS) and 98% specificity (ruling out healthy individuals), resulting in a combined diagnostic accuracy of about 96% in the small study cohort.
However, experts caution that these findings are early and limited: the research involved a relatively small group of severely affected participants, and results haven’t yet been validated in broader, more diverse populations or compared against other illnesses with similar symptoms. More extensive studies are needed before this approach could become a reliable, widely accessible clinical test.
Reference
Annesley, S. (2025, October 19). Can a New Blood Test Actually Detect ME/CFS? Here’s What We Know. ScienceAlert. https://www.sciencealert.com/can-a-new-blood-test-actually-detect-me-cfs-heres-what-we-know?fbclid=IwdGRzaANmfgNjbGNrA2Z962V4dG4DYWVtAjExAAEeQmns7IuqwVC15js2PCtF2r80W_8PpHWmetW9V96zh4PGrc5502P0866nWL8_aem_kmUfpS3mmvPPW2hTcCEhGQ