Hurwitz study shows that patients with severe CFS have a 13.26% shortage of red blood cell volume (RBCV) and patients with non-severe CFS have a 5.82% shortage of RBCV. I think that this anemia could be explained by the inhibitory effect of cytokines on the erythropoiesis. Anemia of chronic disease is is a form of anemia seen in chronic illness, e.g. from chronic infection, chronic immune activation, or malignancy. Weiss and Goodnough did an excellent review on the anemic effects of inflammation. http://www.med.unc.edu/medclerk/medselect/files/anemia2.pdf They describe the effects of different kinds of cytokines on iron metabolism and EPO production/erythropoiesis: TNF alfa: *Degradation erythrocytes? *EPO production? *Erythropoiesis? Interferon gamma: *EPO production? *Erythropoiesis? *Ferroportin-1? *Divalent metal transporter-1 (DMT-1)? Interleukin-1: *EPO production? *Erythropoiesis? *Ferritin ? Interleukin-6: *Ferritin? *Hepcidin? > Fe2+ absorption? Ferroportin-1? Erythropoiesis? Interleukin-10: *Ferritin? *Transferrin-receptor expression? So if you have low iron or low transferrin or high ferritin or high hepcidin, you could have an anemia of chronic disease! Note: In ME/CFS hemoglobin and hematocrit are unreliable markers for anemia. The only way to make sure you are anemic is by a red blood cell volume determination.