Based on indicators such as the size of red blood cells and the concentration of hemoglobin they contain, anemia is generally classified into microcytic hypochromic anemia, normocytic normochromic anemia, or macrocytic anemia. The type of anemia mainly associated with chronic renal failure is normocytic normochromic anemia.

This is because the anemia caused by chronic renal failure is primarily due to a decrease in the secretion of erythropoietin by the kidneys, which is a hormone that promotes bone marrow hematopoiesis. When renal failure occurs, the secretion of this hormone decreases, leading to insufficient bone marrow hematopoiesis, resulting in normocytic normochromic anemia in patients. However, a small portion of patients may also have concurrent anemia, exhibiting features of microcytic hypochromic anemia as well.