Polyglobulia had been traditionally accepted as a secondary event due to chronic hypoxemia occurring in a great proportion of COPD patients [2,27]; nevertheless, it has been supposed that the normal values found in the majority of COPD patients are the result of a balance between the trend towards a decreased red cell mass and an opposite trend towards an increased red cell mass due to the erythropoietic effect of erythropoietin in these subjects [28]. This evidence concerns the gene EPO and chronic obstructive pulmonary disease.