Yamazaki, Tadahiro, Mancini, Donna M, Blate, Michelle et al. · Physiological reports · 2026 · DOI
Researchers measured blood volume in 49 adults with ME/CFS and tested how their bodies responded to standing (using a lean test). They found that about half had abnormal responses to position changes, but these abnormalities were not clearly linked to whether participants had low, normal, or high blood volume. The findings suggest that other body systems—like nerve function or blood vessel control—may be more important than blood volume alone in explaining why many ME/CFS patients feel dizzy or unwell when standing.
Orthostatic intolerance (dizziness, palpitations, or syncope on standing) is a frequent and disabling symptom in ME/CFS. This study addresses a long-standing hypothesis that low blood volume causes orthostatic problems in ME/CFS; the null finding redirects attention toward other physiological systems (autonomic nervous system, vascular tone, breathing control) and may inform future diagnostic and management approaches.
This study does not establish which mechanisms actually cause orthostatic intolerance in ME/CFS; it only rules out static blood-volume measures as a simple correlate. It does not test whether dynamic changes in blood volume during position change, or other aspects of cardiovascular control, are relevant. The cross-sectional design cannot infer causation, and a sample of 49 limits generalisability. The unknown peer-review status and absence of control-group comparison further limit interpretability.
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
Yamazaki, Tadahiro, Mancini, Donna M, Blate, Michelle, Quan, Patrick, Norweg, Anna, Cook, Dane B, et al. (2026). Total blood volume and red blood cell volume are not associated with orthostatic intolerance in adults with myalgic encephalomyelitis/chronic fatigue syndrome.. Physiological reports. https://doi.org/10.14814/phy2.71087
BibTeX
@article{mecfsatlas-yamazaki-2026-total-blood,
author = {Yamazaki, Tadahiro and Mancini, Donna M and Blate, Michelle and Quan, Patrick and Norweg, Anna and Cook, Dane B and Natelson, Benjamin H},
title = {Total blood volume and red blood cell volume are not associated with orthostatic intolerance in adults with myalgic encephalomyelitis/chronic fatigue syndrome.},
journal = {Physiological reports},
year = {2026},
doi = {10.14814/phy2.71087},
note = {PubMed: 42717554},
url = {https://www.mecfsatlas.com/evidence/yamazaki-2026-total-blood},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-10-15. https://www.mecfsatlas.com/evidence/yamazaki-2026-total-blood
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