CBC Methods and Interpretation Flashcards
List 3 anticoagulants and the preferred use for each. Also include the color of tube that has the anticoagulant and what each binds.
- ETDA (purple top tube): preferred anticoagulant for CBC because cell morphology is well preserved: binds divalent cations
- Heparin (green top): Used for CBC’s in non-mammalian species where the volume is limited. This is not ideal, however, because it alters morphology and staining; potentiates antithrombin III, which is an endogenous anticoagulant
- Sodium Citrate (blue top): Used for coagulation studies since the coagulation can be reversed by adding more Ca2+ and platelet counts; binds to calcium cation Ca2+
Describe the difference between plasma and serum.
- Plasma: Fluid part of anticoagulated blood after centrifugation. It contains albumin, globulins, fibrinogen, and coagulation factors
- Serum: Fluid portion after whole blood clots and is centrifuged. It does not contain clotting factors.
List and describe two types of stains used for routine evaluation of a blood smear.
- Wright’s Stain: A mix of blue and orange dyes that stains DNA, RNA, and bacteria (acidic structures) blue or purple, and proteins (basic structures) reddish orange
- Quick stains (Diff-quik) use blue and orange dyes also stain acidic structures such as DNA, RNA and bacteria blue or purple and basic structures such as proteins reddish orange, but may overstrain or blur nuclei
List 2 RBC morphologic features that are best detected using new methylene blue staining.
- Reticulocytes
2. Heniz Bodies
List the results on a CBC that will be artifactually altered by sample lipemia.
- False increase in total plasma protein when using the refractometer
- False increase in hemoglobin
List the results on a CBC that will be artifactually altered by sample hemolysis
- Reading the scale of the refractometer will be interfered
- False increase in hemoglobin
Define and interpret erythrocyte indices (numerical values used to describe RBC’s and characterize anemia) such as MCV, MCHC, RDW.
- MCV: Mean Corpuscular Volume; the mean volume of RBC’s in femtoliter (fL); it is measured by automated analyzers
- MCHC: Mean corpuscular hemoglobin concentration; Ratio of hemoglobin to a volume of RBC’s; False increases can be caused by error in hemoglobin or RBC count, excess EDTA, lipemia, hemolysis, RBC agglutination, or heinz bodies
- RDW: Red cell distribution width; Numerical expression of variation in RBC size (anisocytosis); May increase during microcytosis or macrocytosis, or before abnormal MCV
Interpret a reticulocyte count.
- Should be 1/2 hemoglobin
- Reticulocytes are immature, enucleated RBC’s that still have ribosomes and mitochondria to synthesize hemoglobin. Their organelles stain with new methylene blue.
- Increased reticulocytes = regenerative anemia
- Normal reticulocytes = non regenerative anemia
- Aggregate or punctuate in cats, but only aggregated reticulocytes are counted because they reflect the current bone marrow response
Describe the appearance and significance of RBC rouleaux and RBC agglutination. What test can be performed to distinguish the two?
- RBC rouleaux: looks like stacks of coins; can be normal in cats and horses; may indicate increased proteins due to inflammation
- RBC Agglutination: Irregular clumps of RBC’s due to antibody coating of RBC’s in animals with immune mediated hypolytic anemia
- Test: Saline dispersion test can be used. Saline will disperse rouleaux, but not agglutination
List the leukocytes found in mammalian blood.
Granulocytes: Neutrophils, eosinophils, basophils
Mononuclear Cells: lymphocytes, monocytes
Describe the morphology and clinical significance of acanthocytes.
- Unevenly distributed, irregular, thorny projections
- Due to excess cholesterol in RBC membrane and is reported with liver disease, disseminated intravascular coagulation (DIC), hemangiosarcoma, splenic disease
Describe the morphology and clinical significance of anisocytosis.
- Variation in RBC size
- RDW (Red Cell Distribution Width) is the numerical value of this
- May increase with regenerative response or iron deficiency
Describe the morphology and clinical significance of basophilic stippling.
- Multiple, punctuate basophilic gransules consisting of ribosomes and polyribosomes
- Means regenerative anemia in ruminants and lead toxicity in dogs
Describe the morphology and clinical significance of echinocytes.
- Uniformly spaced, numerous, short projections
- Caused by slow drying (crenation)
- Due to lymphoma, rattlesnake bites, glomerulonephritis, chemotherapy in dogs, after exercise in horses
Describe the morphology and clinical significance of eccentrocytes.
- Hemoglobin is condensed at one end of the cell
- Due to oxidative injury to the cell membrane, such as zinc toxicity in dogs or red maple leaf toxicity in horses
Describe the morphology and clinical significance of heinz bodies.
- Denatured or precipitated hemoglobin protrudes form RBC surface
- Induced by oxidants, drugs, and toxins
Describe the morphology and clinical significance of Howell-jolly bodies.
- Round, basophilic body (looks like a small dot) within the cell caused by a nuclear fragment
- Caused by increased regenerative anemia, extramedullary hematopoiesis, or scenic dysfunction
Describe the morphology and clinical significance of leptocytes.
- Folded Cell
- Often nonspecific clinical significance
- Increased surface area to volume ratio
- Can be seen in liver disease, hypothyroidism, iron deficiency, or chronic disease
Describe the morphology and clinical significance of poikilocytes.
- RBC with an abnormal shape
- Variable diagnostic significance, normal in calves and goats, may occur from chemotherapy in cats with liver disease
Describe the morphology and clinical significance of schistocytes.
-RBC fragments caused by mechanical trauma, disseminated intravascular coagulation, vascular neoplasms, vasculitis, or altered vascular flow
Describe the morphology and clinical significance of macrocytic.
Increased MCV (Mean corpuscular volume)
Describe the morphology and clinical significance of target cells.
- Look like a target
- Increased surface area to volume ratio
- -Can be seen in liver disease, hypothyroidism, iron deficiency, or chronic disease
Describe the morphology and clinical significance of reticulocytosis.
- -Reticulocytes are immature, enucleated RBC’s that still have ribosomes and mitochondria to synthesize hemoglobin. Their organelles stain with new methylene blue.
- Characterizes anemia
Describe the morphology and clinical significance of normocytic.
Normal Mean Corpuscular Volume
