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Three anticoagulants and how they work.
- 1. EDTA (purple top)- chelates Ca+ ions, which are cofactors required by many of the enzymes in the clotting cascade.
- 2. Heparin (green top)- complexes with a potentiates the ability of antithrombin III (endogenous anticoagulant) to inactivate thrombin and active coagulation factors.
- 3. Sodium citrate (blue top)- Complexes Ca2+.
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______ is the preferred anticoagulant for CBC because...
EDTA; cell morphology is well-preserved.
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EDTA is used for...
CBC and preparing blood films and performing platelet counts for several hours post collection
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when is heparin used?
when the sample volume is limited; can be used for CBC and chemistry
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why is heparin not ideal for CBC?
causes alterations in morphology and staining on the blood film
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What is sodium citrate used for?
coagulation studies and sometimes platelet counts because it can be reversed by addition of more Ca2+.
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what is the difference between plasma and serum?
- Plasma is the fluid part of the blood with anticoagulant after it has been centrifuged.
- Serum is the fluid portion of the blood after a clot has formed; does not contain fibrinogen or coagulation factors.
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What are two stains used for routine evaluation of a blood film?
- 1. Wright's stain- acidic structures (DNA, RNA) blue or purple with methylene blue; basic structures (proteins) orange with eosin.
- 2. Diff Quick- also use orange and blue dyes but maybe over-stain or blue nuclei.
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Ne methylene blue staining is used to detect...
reticulocytes and Heinz bodies
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What parameters of a CBC are artifactually altered by lipemia?
Total plasma protein (falsely increased), hemoglobin concentration (falsely increased), MCHC (falsely increased)
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What parameters of a CBC are artifactually altered by hemolysis?
Total plasma protein (makes it harder to read the scale-refractometry), Hemoglobin concentration (falsely increased), MCHC (falsely increased)
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an expression of the average volume of individual red cells
mean corpuscular volume (MCV)
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how do you calculate MCV?
PCV/ RBC x 10; fl (femtoliter)
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terms used to characterize MCV.
- normocytic= normal MCV
- microcytic= less than normal MCV
- macrocytic= greater than normal MCV
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the ratio of the weight of hemoglobin to the volume of RBCs.
mean corpuscular hemoglobin concentration (MCHC)
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how do you calculate MCHC?
Hgb/ PCV x 100; g/dL
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terms used to characterize MCHC.
- normochromic= normal MCHC
- hypochromic= less than normal MCHC
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what is the normal range for MCHC in most species?
32-36 g/dL
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a numerical expression of variation in RBC size (aka _____)
re cell distribution width (RDW); anisocytosis
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RDW can be increased in cases of.....
microcytsis or macrocytosis
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when an animal is macrocytic, it can be indicative of...
anemia; younger cells are being released (increased MCV)
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when an animal is microcytic, it can be indicative of...
iron deficiency (lower than normal MCV)
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when an animal is hypochromic, it can be indicative of...
regenerative anemia (younger cells) or chronic iron deficiency (lower than normal MCHC)
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Why is it important that an animal is as calm as possible before collecting a blood sample?
Epinephrine causes abnormalities in a CBC
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What is the composition of the Buffy coat?
Platelets, WBCs (neutrophils, eosinophils, basophils, lymphocytes, and monocytes)
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What is contained in the plasma of blood that has been spun down?
Albumin, globulins, fibrinogen, and coagulation factors
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Albumin regulates _____ and serves as a ______.
Oncontic pressure; transport molecule
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Globulins in crease in response to _____.
Inflammation
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Carriers for fibrinogen, antibodies, electrolytes, hormones, and clotting factors.
Globulins
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Biliruben is released when __________; icterus is indicative of...
RBCs are broken down; anemia or hepatic disorder
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If lipemia is not a result of a fatty meal, it can be indicative of ...(3)
Diabetic ketoacidosis, hypothyroidism, lipid disorder
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How is plasma protein measured?
Break microhematicrit tube above Buffy coat, empty plasma onto refractometer, record reading
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False increases in total plasma protein can be caused by...(3)
Lipemia, excess EDTA in sample, marked hyperglycemia
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Low PCV is indicative of ______; high PCV is indicative of _____.
Anemia; erythrocytosis
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As a rule of thumb, Hgb conc should equal...
PCV/3
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Hgb conc can have false increase due to... (3)
Hemolysis, lipemia, Heinz bodies
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Errors in MCHC may result from... (5)
Lipemia, hemolysis, Heinz bodies, excess anticoagulant, agglutination
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how do you interpret a reticulocyte count? (getting values)
- to get the absolute value, multiply the % reticulocytes by the RBC count.
- to get corrected reticulocyte percentage, PCV/ mean normal PCV x % reticulocytes.
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anemia is regenerative if...
reticulocyte count is increased
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anemia is non-regenerative if...
there is no significant reticulocytosis
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what are the two feline reticulocyte morphologies and how are they considered in a reticulocyte count?
- aggregated-large clumps of stained reticulum-INCLUDED
- punctuate-pinpoint clumps (more mature)- NOT INCLUDED
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Horses do not release ____ in a response to anemia.
reticulocytes
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Rouleaux is the __________ due to...
stacking of RBCs in linear chains; negative surface charge on RBCs is interfered with.
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autoagglutination is the _________ due to...
irregular clumping of RBCs due to coating of antibodies
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Autoagglutination may be indicative of...
immune-mediated hemolytic anemia
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Roulaux may be normal in _______; in other species, it may indicate...
cats and horses; hypoproteinemia (inflammation)
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How do you differentiate roulaux from autoagglutination?
Saline Dispersion Test-several drops of saline to 1 drop of blood (anticoagulated); saline will disperse roulaux but not autoagglutination
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What two RBC morphologic changes are associated with oxidative injury to RBCs?
heinz bodies, eccentrocyte
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what leukocytes are found in mammalian blood?
neutrophil, basophil, eosinophil, lymphocyte, and monocyte
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irregular thorny projections that are unevenly distributed resulting from altered lipid content of the RBC membrane.
acanthocytes (spur cells)
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Acanthocytes can be indicative of... (4)
liver disease (hepatic lipidosis), DIC, iron deficiency, glomerulonephritis
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RBCs of unequal size, often indicative of a regenerative response or iron deficiency.
anisocytosis
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basophilic stippling is indicative of...
regenerative anemia in ruminants; lead toxicity in dogs
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RBC with numerous, blunt to sharp projections that are uniform in spacing and size.
echinocytes
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echinocytes are indicative of...
crenation (in vitro artifact); lymphoma, glomerulonephritis, toxicosis in dogs (when in vivo)
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When Hgb is condensed at one side of the cell and the RBC membrane collapsed and fused the other side.
Eccentrocyte
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Denatured or precipitated Hgb that often protrudes from the surface of the RBC.
Heinz body
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Nuclear fragment that forms a round basophilic inclusion.
Howell-jolly body
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Howell-jolly bodies are indicative of... (2)
splenic dusfunction, EMJH
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Increased surface area to volume ratio resulting in extra folds in the membrane.
Leptocytes (folded cells) and Target Cells (codocytes)
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Leptocytes and target cells are often...
non-specific/ clinically insignificant findings
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A RBC with an abnormal shape.
Poikilocyte
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Poikilocytes may be normal or they may be indicative of... (2)
artifact of chemotherapy, liver disease in cats
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Formed when antibodies bind to the RBC surface and a portion of the cell is phagocytized by a macrophage; shape of RBC changes- no zone of central pallor.
Spherocyte
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Spherocytes may be indicative of...
immune-mediated hemolytic anemia (IHA)
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RBC fragments caused by mechanical damage.
schistoytes
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Schistocytes may be indicative of... (3)
Disseminated intravascular coagulation (DIC), vascular neoplasms, vasculitis
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