Causes
The issue is thought of as representing any of the following:

An acute loss of blood of a substantial volume;
a decreased production of normal-sized red blood cells (e.g., anemia of chronic disease, aplastic anemia);
an increased production of HbS as seen in sickle cell disease (not sickle cell trait);
an increased destruction or loss of red blood cells (e.g., hemolysis, posthemorrhagic anemia, hypersplenism);
an uncompensated increase in plasma volume (e.g., pregnancy, fluid overload);
a B2 (riboflavin) deficiency
a B6 (pyridoxine) deficiency
or a mixture of conditions producing microcytic and macrocytic anemia.Blood loss, suppressed production of RBCs or hemolysis represent most cases of normocytic anemia. In blood loss, morphologic findings are generally unremarkable, except after 12 to 24 hrs where polychromasia appears. For reduced production of RBCs, like with low erythropoietin, the RBC morphology is unremarkable. Patients with disordered RBC production, e.g. myelodysplastic syndrome, may have a dual population of elliptocytes, teardrop cells, or other poikilocytes as well as a nucleated RBCs. Hemolysis will often demonstrate poikilocytes specific to a cause or mechanism, e.g. bite cells and/or blister cells for oxidative hemolysis, acanthocytes for pyruvate kinase deficiency or McLeod phenotype, sickle cells for sickle cell anemia, spherocytes for immune-mediated hemolysis or hereditary spherocytosis, elliptocytosis for iron deficiency or hereditary elliptocytosis and schistocytes for intravascular hemolysis. Many hemolytic anemias show multiple poikilocytes such as G6PD deficiency, which may show blister and bites cells as well as shistocytes. Neonatal hemolysis may not follow the classic patterns as in adults. Treatment
Treatment will depend on the cause of the normocytic anemia.
References
External links
CeeNu (lomustine) Capsules data sheet published by the FDA
Lomustine at the US National Library of Medicine Medical Subject Headings (MeSH)
Diseases Database (DDB): 29525