American researchers looked for objective ways to evaluate fatigue and pain in patients with CFS, patients with MS and healthy controls. Blood samples were compared to patients’ assessment of their pain and fatigue following sustained moderate exercise.
They found that postexercise mRNA (messenger ribonucleic acid) increases in metabolite-detecting receptors were unique to patients with CFS, whereas both patients with MS and patients with CFS showed abnormal increases in adrenergic receptors. Among patients with MS, greater fatigue was correlated with blunted immune marker expression.