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NOTE

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*The views expressed in this presentation are those of the author and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States government.

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I am a military service member. This work was prepared as part of my official duties. Title 17, USC, §105 provides that “Copyright protection under this title is not available for any work of the U.S. Government.” Title 17, USC, §101 defines a US Government work as a work prepared by a military service member or employee of the US Government as part of that person’s official duties

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ANEMIA

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RED BLOOD CELL (RBC) INDICES

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  • Hematocrit (HCT): Volume percentage of RBCs in blood. See Table 12-1 for age-related normal levels

  • Mean corpuscular volume (MCV): Average RBC volume

  • Mean corpuscular hemoglobin (MCH): Average quantity of hemoglobin per RBC

  • Mean corpuscular hemoglobin concentration (MCHC): Grams of hemoglobin per 100 mL of packed RBCs (amount of hemoglobin per unit volume)

  • Red cell distribution width (RDW): Index of the variation in RBC size

  • Reticulocyte count: Percentage of young RBCs in the plasma

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Table Graphic Jump Location
TABLE 12-1

Normal Hemoglobin, Hematocrit, and Mean Corpuscular Volume Values by Age*

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DIFFERENTIAL DIAGNOSIS BASED ON MEAN CORPUSCULAR VOLUME

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Microcytic Anemia

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  • Iron deficiency, thalassemia, anemia of inflammation, lead poisoning, sideroblastic anemia, copper deficiency

  • Iron deficiency versus thalassemia trait: RBC count and RDW are often normal in thalassemia trait; in iron deficiency, low RBC count and elevated RDW; Mentzer index (MCV/RBC) serves as useful screen (<13 suggests thalassemia trait, >13 suggests iron deficiency)

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Normocytic Anemia

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  • In normocytic anemia, assess the reticulocyte count. The reticulocyte index accurately reflects erythropoiesis by adjusting for the degree of anemia

  • Reticulocyte index (RI) = % Reticulocyte × Patient HCT/Normal HCT

  • RI is greater than 3% in compensated bleeding or hemolysis and less than 2% in anemia due to decreased RBC production; 1% is normal marrow activity without anemia

  • Reticulocytes low: Pure RBC dysplasia (Diamond–Blackfan anemia), transient erythroblastopenia of childhood, aplastic crisis (e.g., secondary to parvovirus B19 infection), renal disease; acute bleed (without compensation), marrow infiltration (e.g., leukemia, solid tumor, or hemophagocytosis), marrow aplasia ...

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