Dx Methods 1-3 - The CBC (2).pptx
Transcript
You Complete Me: The Complete Blood Count ME 523 – Diagnostic Methods I Michael A. Sharma, MPAS, PA-C Emergency Medicine, UT Southwestern Medical Center, Dallas, TX Adjunct Professor, Franklin Pierce University, Austin, TX https://go.oncehub.com/MichaelSharma | Complete Blood Count (CBC) A count of...
You Complete Me: The Complete Blood Count ME 523 – Diagnostic Methods I Michael A. Sharma, MPAS, PA-C Emergency Medicine, UT Southwestern Medical Center, Dallas, TX Adjunct Professor, Franklin Pierce University, Austin, TX https://go.oncehub.com/MichaelSharma | Complete Blood Count (CBC) A count of the different major components of blood White blood cells (WBCs) Red blood cells (RBCs) Platelets Descriptions about the different major components of blood, mostly focusing on RBCs Usually done with a WBC differential or “diff” count & percentage of the different forms of WBCs Red Blood Cells (RBCs) A count of the number of RBCs in a given volume of blood as obtained by automated counters. Less useful than Hb or Hct Normal range: 4.2–5.4 cells/μL in women and 4.4–6.0 cells/μL in men cells per microliter… 1/1,000,000 liters Red Blood Cells (RBCs) Increased in Polycythemia vera & other myeloproliferative dz Severe dehydration Decreased in Anemia Abnormal RBC Morphology Automated counters will note abnormal RBC shapes; personnel can then examine under microscope Hemoglobin (Hgb or Hb) A measurement of the oxygen carrying capacity of blood Depends on the number of RBCs the amount of hemoglobin in each RBC Measured in grams per deciliter – g / dL Men: 14-18 g/dL Women: 12-16 g/dL Lagging indicator of acute blood loss Point-of-care Hgb testing (HemoCue) is available Hematocrit (Hct) An indirect estimate of the number of RBCs Thus, an indirect estimate of the amount of hemoglobin After centrifuging a portion of whole blood: the height of the RBC mass is measured compared to the height of the entire column of blood Expressed as a percentage – the % of blood that is RBCs Hematocrit (Hct) Normal range Men: 37–47% Women: 42–52% Decreased: all anemias Increased: high altitude advanced cardiac or pulmonary disease Polycythemia vera and other diseases of bone marrow (myeloproliferative diseases) Hgb & Hct – Like Peas and Carrots These are often referred to together: H&H Hgb & Hct The Hct can be calculated from the Hgb (Hgb x 3) +/- 3 = Hct Quick indicator of correct functioning of the hematology analyzer RBC Indices Mean Corpuscular Volume (MCV) Mean Corpuscular Hgb (MCH) Mean Corpuscular Hgb Content (MCHC) RBC Distribution Width (RDW) Mean Corpuscular Volume (MCV) Average RBC volume; when anemia is present, classifies it as: Normocytic Microcytic (decreased MCV) Macrocytic (increased MCV) Reference range: 80-100 fL/cell fL = 10-15 L Calculated by dividing the hematocrit value by the RBC count MCV (fL/cell) = (Hct/RBC count) x 10 Newer automated analyzers measure MCV directly Mean Corpuscular Volume (MCV) Increased in Macrocytic anemias Alcoholism Decreased in Iron deficiency anemias Thalassemias Lead poisoning Anemia of chronic disease and other hemoglobinopathies (may be decreased or normal) Limitations MCV may be affected by marked leukocytosis, numerous large platelets, methanol poisoning, marked hyperglycemia, in vitro hemolysis or fragmentation of RBCs. Mean Corpuscular Hgb (MCH) Function: estimates the average weight of hemoglobin in each RBC Reference Range: 26-34 pg/cell pg = 10-12 g Calculated by dividing the hemoglobin level by the RBC count MCH (pg/cell) = (Hgb/RBC count) x 10 Mean Corpuscular Hgb Content (MCHC) Function: estimates the concentration of hemoglobin in each RBC Ratio of the weight of hemoglobin to the volume of the RBC Reference Range: 31-37 g/dL (310-370 g/L) Calculated by dividing the hemoglobin by the hematocrit value MCHC (g/dL) = (Hgb/Hct) x 100 RBC Distribution Width (RDW) Measure of anisocytosis – size variation in a population of RBCs An (not) iso (same) cytosis (cells) It measures the width of distribution, not the width of cells Reference Range: 6 lobes Commonly seen in patients with megaloblastic anemia Neutrophil hyposegmentation: many neutrophil nuclei are bilobed (two lobes, i.e. dumbbell shaped) more band forms are also seen Neutrophil Band 31 Hypersegmented Neutrophil 32 Pelger-Huet Anomaly (hyposegmentation) 33 Reactive Lymphocytes Normally will be
