Reticulocytes

Reticulocytes are immature RBCs that do no contain nuclei but have increased amounts of RNA. On normal peripheral blood smears stained with Wright-Giemsa they appear as polychromatophilic cells (light purple/blue cells are the polychromatophilic cells versus the more mature RBCs stain pink/red) and with special stains (such as supravital stain) one could highlight the excess RNA within the cytoplasm of these RBCs known as reticulocytes. Normal range for reticulocytes in the peripheral blood is 0.5-1.5%. Increased reticulocytes can be seen in the setting of anemias that are due to desctruction of RBCs (such as in autoimmune hemolytic anemia) which causes the marrow to increase production of newer RBCs. Low recticulocytes are usually indicative of marrow underproduction and can be caused by chemotherapy, aplastic anemia, pernicious anemia, bone marrow malignancies, vitamin and mineral deficiencies, chronic diseases, or lack of erythropoietin production.