Even though a simple and unequivocal explanation of the effect of increased RDW on outcomes cannot be given so far, several biological and metabolic abnormalities associated with different human disorders can exert a considerable effect on erythropoiesis including oxidative stress, inflammation, poor nutritional status, dyslipidemia, erythrocyte fragmentation, decline of erythropoietin synthesis, and erythropoietin hyporesponsiveness [2]. Here, EPO is linked to metabolic syndrome.