Complete Blood Count Flashcards
Explain how flow cytometry and Coulter principle are used to generate CBC results.
Flow cytometry exploits the differences in cell size, complexity, and DNA/RNA content, and counts the number of all cells except RBCs.
RBCs are counted using the coulter principle, which states that particles pulled through an orifice, concurrent with an electric current, produce a charge impedance that is proportional to the volume of the particle traversing the orifice. This allows for RBCs to be separated.
Define RBC count
Number of Red Blood cells present, measured in millions per microliter or 10^12 per liter
Define Hemoglobin (HGB)
In vitro measurement of the concentration of hemoglobin released by lysed RBCs into the whole blood. Measured spectrophotometrically by converting hemoglobin into cyanmethemoglobin. Units are g/dL or g/L.
Define Hematocrit (HCT)
Measure of how much of a given volume of whole blood is occupied by RBCs. Can be expressed as a percentage of whole blood, or in terms of liters per liter. (Calculated by RBC * MCV)
Rule of thumb: HCT= 3* HGB
Define Mean Cell Volume (MCV)
Mean size of the RBCs counted, determined from Coulter Prinicple or manually, using equation MCV=(HCT/RBC)*10
Measured in femoliters (10^-15 L)
Define Mean Cell Hemoglobin (MCH)
Mean quantity of Hemoglobin in a single red cell; parallels MCV.
Calculated via equation MCH= HGB/RBC
Measured in picograms (10^-12 g)
Define Mean Cell Hemoglobin Concentration (MCHC)
Average concetration of hemoglobin in a single red cell or concentration of hemoglobin in packed red cells. Calculated via equation MCHC= HGB/HCT
Measured in g/dL or g/L
Abnormalities based on RBC
Anemia: Decreased due to blood loss, peripheral destruction, or insufficient erythropoiesis in the marrow.
Erythrocytosis/Polycythemia: Increased due to reactive changes (smoking, renal cell carcinoma), thalassemia, or primary marrow neoplasm (polycythemia vera)
Abnormalities based on HGB
Anemia: decreased
Erythrocytosis/Polycythemia: Increased
Abnormalities based on HCT
Decreased due to anemia or fluid overload
Increased due to erythcytosis/polycythemia or dehydration
Abnormalities based on MCV
Decreased: Microcytosis, iron deficiency anemia, or thalassemia
Increased: Macrocytosis, megaloblastic anemia
Abnormalities based on MCH
Decreased: Hypochromatic, iron deficiency anemia
Increased: Hyperchromatic, magloblastic anemia
Abnormalities based on MCHC
Decreased in moderate to severe micocytic anemia
Increased in hereditary spherocytosis
Define White Blood Cell Count (WBC)
Number of white blood cells in whole blood, obtained using Coulter principle.
Neutrophil
Diameter 9-15 microns
Cytoplasm slightly acidophilic
Many very fine granules
2-5 nuclear segments/lobes
Eosinophil
Diameter 12-17 microns
Numerous large, round red-orange granules
1-4 nuclear lobes, usually 2
Basophil
Diameter 12 microns
Numerous large, round, purple-black cytoplasmic granules
Usually two nuclear lobes, often covered by granules
Monocyte
Diameter 15-30 microns
Large and eccentric nucleus, round kidney/horshoe shaped or lobulated
Chromatin has a skein-like or lace appareance
Abundant cytoplasm, grayish-blue, few to many fine azurophilic granules
May have intracytoplasmic vacuoles
Lymphocyte
Diameter: 7-12 microns Mostly small, can be large if reactive Nucleus round or slightly indented Condensed chromatin Usually scanty bluish cytoplasm, may contain a few azurophilic granules
Abnormal RBC morphology
Decreased: RBC, HCT, MCV, MCH, MCHC
Increased RDW
e.g Iron deficiency anemia (low RBC)
Spherocytes
Bite Cells (associated with G6PD deficiency)
Schistocytes (fragments rbcs)
Target cells
Sickle cells
Basophilic stippling (evenly dispersed fin blue granules)
Howell-Jolly bodies (Single dense blue dot)
Heinze body (denatured/oxidized hemoglobin attached to the inner cell membrane)
Abnormal WBC morphology
Dohle Body (pale blue inclusion at the periphery of the cytoplasm) Toxic Granulation (Hypergranularity, increased numbers and prominence of primary granules) Hypersegmented neutrophils (more than 5 lobes, associated with megaloblastic anemia)
Platelet count
Obtained using Coulter Principle, measured in thousands/microliter or billions per liter.
Platelets are small fragments of megakaryocyte cytoplasm. Diameter 2-3 microns, average volume 7-8 fL.
Irregulare outline, light blue cytoplasm. Many small azurophilic granules.
Platelet abnormalities
Thrombocytopenia: decreased platelet count
Thrombocytosis: Increased platelet count
