GSTM1 and anemia: One example of the dual response to hypoxia is erythropoiesis: while altitude hypoxia increases blood hemoglobin (Hb) potentially enhancing the blood oxygen transport, the pulmonary hypoxia in pulmonary diseases patients is often associated with anemia, likely due to impaired iron handling by hepcidin (Hep) and dysregulated transferrin receptor expression, secondary to inflammation [1].