Several factors such as anemia, malnutrition, bone marrow depression, erythropoietin use, thyroid dysfunction, iron or vitamin B12 deficiency, cardiovascular disease, increased angiotensin II, renal or liver dysfunction, acute or chronic inflammation, among others, have been shown to affect RDW values [44,45,74, 75–77. This evidence concerns the gene EPO and vitamin B12 deficiency.