Blood Volume Status in ME/CFS Correlates With the Presence or Absence of Orthostatic Symptoms: Preliminary Results.
van Campen, C Linda M C, Rowe, Peter C, Visser, Frans C · Frontiers in pediatrics · 2018 · DOI
Quick Summary
This study measured the amount of blood circulating in the bodies of 20 adults with ME/CFS and found that those with symptoms of dizziness or lightheadedness when standing up had significantly less blood volume than those without these symptoms. On average, all ME/CFS patients had about 11 milliliters less blood per kilogram of body weight than expected, but the drop was much more pronounced in patients with orthostatic symptoms. This finding suggests that reduced blood volume may be connected to specific symptoms some ME/CFS patients experience.
Why It Matters
Understanding the relationship between blood volume reduction and orthostatic symptoms could help clinicians identify which ME/CFS patients might benefit from blood volume-expanding interventions, potentially improving a debilitating symptom for many patients. This study provides objective evidence that blood volume abnormalities in ME/CFS are not uniform across all patients but correlate with specific symptoms, suggesting a biologically meaningful subgroup that warrants further investigation.
Observed Findings
Patients with orthostatic intolerance had mean absolute blood volume of 56 ml/kg compared to 66 ml/kg in those without OI (p<0.05).
All 20 ME/CFS patients had reduced blood volume averaging 11 ml/kg below reference values.
The blood volume deficit relative to predicted normal values was -14 ml/kg in OI patients versus -4 ml/kg in non-OI patients (p<0.02).
40% of study participants (8 of 20) had clinical suspicion of orthostatic intolerance.
Inferred Conclusions
Blood volume reduction in ME/CFS is not universal but is significantly more pronounced in patients with orthostatic intolerance symptoms.
Accountting for orthostatic symptoms could improve detection and characterization of the blood volume-reduced subset within the ME/CFS population.
Orthostatic intolerance in ME/CFS may represent a biologically distinct subgroup with measurable hemodynamic abnormalities.
Remaining Questions
Why do some ME/CFS patients develop reduced blood volume while others do not, and what underlying mechanisms drive this difference?
Would interventions aimed at increasing blood volume (such as increased salt and fluid intake or medications) reduce orthostatic symptoms in this population?
How do blood volume measurements obtained at rest correlate with symptoms that occur specifically during positional changes or prolonged standing?
What This Study Does Not Prove
This study does not prove that reduced blood volume causes orthostatic symptoms—it only shows a correlation between the two. The findings cannot be generalized to all ME/CFS patients due to the small sample size (n=20) and selection of consecutive patients, which may not represent the broader ME/CFS population. The study also does not establish whether blood volume reduction is a primary cause of ME/CFS or a secondary consequence of the disease.
Tags
Symptom:Orthostatic IntoleranceFatigue
Biomarker:Blood Biomarker
Method Flag:Weak Case DefinitionNo ControlsSmall SampleExploratory Only