CBC Methods and Interp.txt
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CBC Methods and Interp.txt
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+.
______ is the preferred anticoagulant for CBC because...
EDTA; cell morphology is well-preserved.
EDTA is used for...
CBC and preparing blood films and performing platelet counts for several hours post collection
when is heparin used?
when the sample volume is limited; can be used for CBC and chemistry
why is heparin not ideal for CBC?
causes alterations in morphology and staining on the blood film
What is sodium citrate used for?
coagulation studies and sometimes platelet counts because it can be reversed by addition of more Ca2+.
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.
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.
Ne methylene blue staining is used to detect...
reticulocytes and Heinz bodies
What parameters of a CBC are artifactually altered by lipemia?
Total plasma protein (falsely increased), hemoglobin concentration (falsely increased), MCHC (falsely increased)
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)
an expression of the average volume of individual red cells
mean corpuscular volume (MCV)
how do you calculate MCV?
PCV/ RBC x 10; fl (femtoliter)
terms used to characterize MCV.
normocytic= normal MCV
microcytic= less than normal MCV
macrocytic= greater than normal MCV
the ratio of the weight of hemoglobin to the volume of RBCs.
mean corpuscular hemoglobin concentration (MCHC)
how do you calculate MCHC?
Hgb/ PCV x 100; g/dL
terms used to characterize MCHC.
normochromic= normal MCHC
hypochromic= less than normal MCHC
what is the normal range for MCHC in most species?
a numerical expression of variation in RBC size (aka _____)
re cell distribution width (RDW); anisocytosis
RDW can be increased in cases of.....
microcytsis or macrocytosis
when an animal is macrocytic, it can be indicative of...
anemia; younger cells are being released (increased MCV)
when an animal is microcytic, it can be indicative of...
iron deficiency (lower than normal MCV)
when an animal is hypochromic, it can be indicative of...
regenerative anemia (younger cells) or chronic iron deficiency (lower than normal MCHC)
Why is it important that an animal is as calm as possible before collecting a blood sample?
Epinephrine causes abnormalities in a CBC
What is the composition of the Buffy coat?
Platelets, WBCs (neutrophils, eosinophils, basophils, lymphocytes, and monocytes)
What is contained in the plasma of blood that has been spun down?
Albumin, globulins, fibrinogen, and coagulation factors
Albumin regulates _____ and serves as a ______.
Oncontic pressure; transport molecule
Globulins in crease in response to _____.
Carriers for fibrinogen, antibodies, electrolytes, hormones, and clotting factors.
Biliruben is released when __________; icterus is indicative of...
RBCs are broken down; anemia or hepatic disorder
If lipemia is not a result of a fatty meal, it can be indicative of ...(3)
Diabetic ketoacidosis, hypothyroidism, lipid disorder
How is plasma protein measured?
Break microhematicrit tube above Buffy coat, empty plasma onto refractometer, record reading
False increases in total plasma protein can be caused by...(3)
Lipemia, excess EDTA in sample, marked hyperglycemia
Low PCV is indicative of ______; high PCV is indicative of _____.
As a rule of thumb, Hgb conc should equal...
Hgb conc can have false increase due to... (3)
Hemolysis, lipemia, Heinz bodies
Errors in MCHC may result from... (5)
Lipemia, hemolysis, Heinz bodies, excess anticoagulant, agglutination
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.
anemia is regenerative if...
reticulocyte count is increased
anemia is non-regenerative if...
there is no significant reticulocytosis
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
Horses do not release ____ in a response to anemia.
Rouleaux is the __________ due to...
stacking of RBCs in linear chains; negative surface charge on RBCs is interfered with.
autoagglutination is the _________ due to...
irregular clumping of RBCs due to coating of antibodies
Autoagglutination may be indicative of...
immune-mediated hemolytic anemia
Roulaux may be normal in _______; in other species, it may indicate...
cats and horses; hypoproteinemia (inflammation)
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
What two RBC morphologic changes are associated with oxidative injury to RBCs?
heinz bodies, eccentrocyte
what leukocytes are found in mammalian blood?
neutrophil, basophil, eosinophil, lymphocyte, and monocyte
irregular thorny projections that are unevenly distributed resulting from altered lipid content of the RBC membrane.
acanthocytes (spur cells)
Acanthocytes can be indicative of... (4)
liver disease (hepatic lipidosis), DIC, iron deficiency, glomerulonephritis
RBCs of unequal size, often indicative of a regenerative response or iron deficiency.
basophilic stippling is indicative of...
regenerative anemia in ruminants; lead toxicity in dogs
RBC with numerous, blunt to sharp projections that are uniform in spacing and size.
echinocytes are indicative of...
crenation (in vitro artifact); lymphoma, glomerulonephritis, toxicosis in dogs (when in vivo)
When Hgb is condensed at one side of the cell and the RBC membrane collapsed and fused the other side.
Denatured or precipitated Hgb that often protrudes from the surface of the RBC.
Nuclear fragment that forms a round basophilic inclusion.
Howell-jolly bodies are indicative of... (2)
splenic dusfunction, EMJH
Increased surface area to volume ratio resulting in extra folds in the membrane.
Leptocytes (folded cells) and Target Cells (codocytes)
Leptocytes and target cells are often...
non-specific/ clinically insignificant findings
A RBC with an abnormal shape.
Poikilocytes may be normal or they may be indicative of... (2)
artifact of chemotherapy, liver disease in cats
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.
Spherocytes may be indicative of...
immune-mediated hemolytic anemia (IHA)
RBC fragments caused by mechanical damage.
Schistocytes may be indicative of... (3)
Disseminated intravascular coagulation (DIC), vascular neoplasms, vasculitis