Anemia of chronic kidney disease (CKD) develops as kidney function declines. Reduced erythropoietin production, iron deficiency, and inflammation are the most important causes of CKD anemia. Anemia in the healthy population is defined by World Health Organization (WHO) criteria: for women, a hemoglobin (Hb) of less than 12 g/dl, and for men, an Hb of less than 13 g/dl. However, for practical purposes, severe anemia in patients with CKD requiring treatment is defined by a threshold Hb of less than 10 g/dl.