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MLAB 1415- Hematology Keri Brophy-Martinez

MLAB 1415- Hematology Keri Brophy-Martinez. Chapter 8: Anemia. Anemia. Anemia is the inability of the blood to supply the tissue with adequate oxygen for proper metabolic function. Clinically, anemia is defined as a decrease in the normal concentration of hemoglobin or erythrocytes.

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MLAB 1415- Hematology Keri Brophy-Martinez

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  1. MLAB 1415- HematologyKeri Brophy-Martinez Chapter 8: Anemia

  2. Anemia • Anemia is the inability of the blood to supply the tissue with adequate oxygen for proper metabolic function. • Clinically, anemia is defined as a decrease in the normal concentration of hemoglobin or erythrocytes. • Anemia is not a disease, but an expression of an underlying disorder or disease.

  3. Development of Anemia • Anemia occurs if: • Erythrocyte loss or destruction exceeds the maximum capacity of bone marrow erythrocyte production OR • Bone marrow erythrocyte production is impaired

  4. Causes of anemia • Acute blood loss (hemorrhage) • Accelerated destruction of RBC’s (immune or non-immune) • Nutritional deficiency (iron, folate or B12) • Bone marrow replacement (e.g. cancer) • Infection • Toxicity • Hematopoietic stem cell arrest or damage • Hereditary or acquired defect

  5. Anemia Classifications • Functional • Uses absolute and corrected retic count, RPI, and serum iron for classification • Types • Survival Defects(Increased Destruction) • Proliferation Defects(Decreased production) • Maturation Defects

  6. Anemia Classifications • Morphologic • Uses erythrocyte indices for classification • Types • Macrocytic, Normochromic • Causes: Folate or B12 deficiency, liver disease • Normocytic, Normochromic • Causes: bone marrow failure, hemolytic anemia, chronic renal failure, leukemia, metastatic malignancy • Microcytic,Hypochromic • Most common anemia • Causes: iron deficiency, sideroblastic anemia, thalassemia, chronic diseases

  7. Diagnosis of anemia • Clinical history • Physical signs such as pallor, fatigue, weakness and shortness of breath • Laboratory tests • CBC • Examination of the blood smear • Reticulocyte - measures effective erythropoiesis • Bone marrow examination • Iron studies - iron, total iron-binding capacity (TIBC), ferritin • Vitamin B12 and folate • Erythropoietin level

  8. Laboratory Tests for Measurement of Anemia

  9. Lab Tests Hemoglobin Hematocrit Reference values Male: 42-52% Female: 36-46% • Reference values • Male: 14-17.4 g/dl • Female: 12-16 g/dl • Moderate anemia: • 7-10 g/dl • Severe anemia: • <7 g/dl

  10. Parameters of the CBC (complete blood count) • Red Blood Count or RBC • Hemoglobin • Hematocrit • Note: the approximate relationship of the hemoglobin to the hematocrit is 1:3. This may vary with the cause of the anemia and the effect on the RBC indices, especially the MCV. • RBC indices • MCV - mean cell volume • Normal:80-100 fL (femtoliters) • Measured directly on automated cell counters • Used to classify RBCs as normocytic, microcytic or macrocytic • Indicates the average volume of the red cells Calculation: Hct x 10 RBC

  11. RBC Indices con’t • MCH - mean cell hemoglobin weight • Normal: 28-34 pg • A measurement of the hemoglobin content in RBC’s Calculation: Hgb x 10 RBC • MCHC - mean cell hemoglobin concentration • Normal: 32-36 % • Used to classify RBCs as normochromic, or hypochromic • A measure of the concentration of hemoglobin in the average RBC Calculation: Hgb x 100 Hct

  12. Parameters of the CBC (complete blood count) • RDW -Red Cell Distribution Width • Calculated index used to identify anisocytosis • Normal: 11.5-14.5% Calculation: Standard deviation of MCV x100 Mean MCV

  13. Reticulocyte • Adult reference range: 0.5 - 2.5% • Useful in determining the response to the anemia and the potential of the bone marrow to manufacture RBC’s. Expressed as a percentage of the RBC’s. • When anemia is present, it is helpful to correct the retic using the patient’s hematocrit in order to assess appropriate bone marrow response • A supravital stain called New Methylene Blue is used to stain reticulocytes. On a Wright’s stained smear, reticulocytes appear as bluish red cells. The term used for retics on Wright’s stain is polychromasia. Corrected retic% = retic % X Patient hct Normal hct* based on age and sex [*Normal female hct = 42%] [*Normal male hct = 45%]

  14. Reticulocyte • Prematurely released retics remain in the blood and take from ½ to 1 ½ days longer to mature. This will cause even the “corrected” retic to be elevated, so a calculation must be performed to correct for this situation to obtain the reticulocyte production index (RPI). A maturation time table is used for this calculation. • Indicator of the adequacy of the bone marrow response in anemia • RPI>2: good bone marrow response • RPI<2: inadequate response RPI = corrected retic maturation time in days

  15. Adult Reference Ranges

  16. References • Harmening, D. M. (2009). Clinical Hematology and Fundamentals of Hemostasis. Philadelphia: F.A Davis. • McKenzie, S. B., & Williams, J. L. (2010). Clinical Laboratory Hematology . Upper Saddle River: Pearson Education, Inc.

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