29 GLOSSARY

absolute neutrophil count (ANC)

a calculation of the number of circulating neutrophils, derived from the total number of white blood cells (WBCs) and the percentage of neutrophils counted in a microscope’s visual field

anemia

decreased red blood cell (RBC) count

aplasia

lack of cellular development (e.g., of cells within the bone marrow)

cytokines

proteins produced by leukocytes that are critical for regulation of hematopoiesis, apoptosis, and immune responses

erythrocyte

a cellular component of blood essential to the transport of oxygen and carbon dioxide (synonym: RBC)

erythroid cells

any cell that is or will become a mature RBC

erythropoietin

hormone produced primarily by the kidneys in response to cellular hypoxia that is necessary for erythropoiesis

haptoglobin

blood protein synthesized by the liver; binds free hemoglobin released from erythrocytes which is then removed by the reticuloendothelial system

hemolysis

destruction of RBCs with release of cellular components into the circulation; may occur within or outside the vasculature

hemosiderin

iron-containing pigment derived from the breakdown of hemoglobin

hypochromia

pallor within the RBCs caused by decreased hemoglobin content

leukemia

uncontrolled proliferation of WBCs

lymphopenia

a lymphocyte count less than 1500/mm³

megaloblastic anemia

a type of anemia characterized by abnormally large, nucleated RBCs

microcytosis

smaller-than normal RBCs

neutropenia

lower-than-normal number of neutrophils

normochromic

normal RBC color, indicating normal amount of hemoglobin

normocytic

normal size of RBC

pancytopenia

abnormal decrease in WBCs, RBCs, and platelets

petechiae

tiny capillary hemorrhages

poikilocytosis

variation in shape of RBCs

polycythemia

excess RBCs

reticulocytes

slightly immature RBCs, usually 1% of total number of circulating RBCs

spherocytes

small, spherically shaped RBCs

thrombocytopenia

lower-than-normal platelet count

thrombocytosis

higher-than-normal platelet count