RBC Disorders I

• RBC precursors start large and become smaller with maturation
• A reticulocyte is a newly formed RBC that still has some RNA

  
• Reticulocyte count can be used to determine cause of anemia
• Methemoglobinemia is decreased oxygen-carrying capacity of hemoglobin due to the conversion of iron from reduced ferrous (Fe2+) state to oxidized ferric (Fe3+) state
• Methemoglobinemia can be acquired or congenital
• Methemoglobinemia can be treated with methylene blue
• Lab Tests for Clearance of Hemoglobin

  Haptoglobin

  LDH

  Bilirubin: unconjugated, conjugated

  Urine free hemoglobin
• Anemia is the reduction of the oxygen-transporting capacity of the blood
• Signs and Symptoms of Anemia

  Fatigue

  Weakness

  Dizziness

  Headache

  Shortness of breath

  Tachycardia

  Pallor

  Pale mucous membranes
• Anemia may be asymptomatic, especially if onset is gradual
• A CBC provides valuable information for benign/reactive and malignant disease processes
• Red blood cell count includes the concentration of RBCs
• Hemoglobin includes the concentration of Hgb (g/dL)
• Hematocrit measure the relative volume of packed RBCs (%)
• Mean Cell Volume measures the average size of RBCs (fL)
• Mean Cell Hemoglobin calculates the average amount of Hgb in each RBC
• Mean Cell Hemoglobin Concentration calculates the average amount of Hgb per a certain concentration of RBCs
• Red Cell Distribution Width is the amount of RBC size variability
• Microcytic means small RBCs, low MCV
• Macrocytic means large RBCs, high MCV
• Hypochromia means decreased Hb in RBCs, low MCHC
• Anisocytosis means variation in cell size, increased RDW
• Poikilocytosis means variation in cell shape
• Polychromasia means bluish color in some cells
• Complete Metabolic Panel is a lab test that includes bilirubin
• Lactate dehydrogenase is released by damaged RBCs and can be tested in a lab
• The Direct antiglobulin test (DAT) is a lab that tests different types of proteins on RBCs
• Haptoglobin binds and clears free hemoglobin and is a useful lab test
• CBC and peripheral blood smear review are key for evaluating and classifying anemia
• Anemia Classification - Mechanism

  Blood loss

  Increased destruction

  Impaired production
• Blood loss can be acute/traumatic or chronic
• Types of Acute/Traumatic Blood Loss

  Hypovolemia/shock

  Hemodilution

  Reticulocytosis
• Reticulocytosis is an increase in immature blood cells
• Hemodilution is an increase in fluid with a decrease in number of RBCs
• Hypovolemia/shock is a loss of all blood elements
• Chronic blood loss often results in iron deficiency anemia