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# Blood Dyscrasias ## Red Blood Cell (Erythrocyte) Values and Morphology * Red blood cells (RBCs or erythrocytes) are biconcave disks that contain hemoglobin (95% of mass), which carries oxygen throughout the body. * The heme portion of the cell contains iron, which binds to the oxygen. * RBCs li...

# Blood Dyscrasias ## Red Blood Cell (Erythrocyte) Values and Morphology * Red blood cells (RBCs or erythrocytes) are biconcave disks that contain hemoglobin (95% of mass), which carries oxygen throughout the body. * The heme portion of the cell contains iron, which binds to the oxygen. * RBCs live about 120 days after which they are destroyed and their hemoglobin is recycled or excreted. * Normal values of red blood cell count vary by age: * Neonate: 4.1-6.1 million per mm³ * 2-6 months: 3.8-5.6 million per mm³ * 1-16 yrs: 3.9-5.3 million per mm³ * 16-18 yrs: 4.2-5.4 million per mm³ ## The most common disorders of RBCs are those that interfere with production, leading to various types of anemia: * Blood loss * Hemolysis * Bone marrow failure ## RBC morphology may vary depending upon the type of anemia: * Size: Normocytes, microcytes, macrocytes * Shape: Spherocytes (round), poikilocytes (irregular), drepanocytes (sickled) * Color (reflecting concentration of hemoglobin): Normochromic, hypochromic ## RED BLOOD CELLS EVALUATION * A number of different tests are used to evaluate the condition and production of red blood cells in addition to the red blood cell count: * **Hemoglobin** - Carries oxygen and is decreased in anemia and increased in polycythemia. * Normal values: * Neonate: 14.5-22.5 g/dl. * 2 months: 9.0-14.0 g/dl. * 6-12 years: 11.5-15.5 g/dl. * 12-18 years: 12-16.0 g/dl. * **Hematocrit** - Indicates the proportion of RBCs in a liter of blood (usually about 3 times the hemoglobin number). * Normal values: * Neonate: 48-69%. * 3 days: 44-75% * 2 months: 28-42% * 6-12 years: 35-45% * 12-18 years: 36-49% * **Mean corpuscular volume (MCV)** - Indicates the size of RBCs and can differentiate types of anemia. * For adults, 100 is macrocytic. * Normal values: * Neonate: 95-121 µm³. * 0.5-2 years: 70-86 µm³. * 6-12 years: 77-95 µm³, * 12-18 years: 78-102 µm³. * **Reticulocyte count** - Measures marrow production and should rise with anemia. * Normal values: 0.5-1.5% of total RBCs.