Term
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Definition
The study of blood (an integral component of clinical patholgoy, internal medicine, immunology, and oncology.
-Evaluation of the pathophysiologic basis for lab analysis and interpretation of the cellular elements of blood (erythrocytes, leukocytes,and platelets) |
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Term
| Define clinical pathology. |
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Definition
| -the examination of tissues or fluids from a living patient using many tools and techniques including chemistry, hematology, hemostatis, enzymology, and immunology, and cytology |
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Term
| Name the primary test for hematologic analysis and describe it |
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Definition
-Complete Blood Count (CBC)
-description:
1. essential part of minimum database; used for screening, dx, and dz monitoring
2. Includes erythrogram, leukogram, platelet analysis, and +/- plasma proteins (therefore WHOLE BLOOD is needed for analysis)
3. Quantitative and qualitative components |
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Term
| List the elements of a CBC. |
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Definition
1. Erythrogram
2. Leukogram
3. Platelets
4. Proteins |
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Term
| List the elements of an Erythrogram |
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Definition
1. Packed cell volume or hematocrit (PCV or HCT)
2. Red blood cell count (RBC)
3. Hemoglobin (Hb)
4. Mean Cell Volume (MCV)
5. Mean cell hemoglobin (MCH)
6. Mean cell hemoglobin concentration (MCHC)
7. Red Cell Distribution Width (RDW)
8. RBC Morphology
9. Reticulocyte count** |
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Term
| List the elements of a leukogram. |
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Definition
1. White blood cell count (WBC)
2. Differential leukocyte count
3. WBC morphology |
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Term
| List the elements of platelets enumeration recorded on a CBC. |
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Definition
1. Platelet count
2. Mean platelet volume (MPV) |
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Term
| List the elements of proteins described on a CBC. |
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Definition
1. Total plasma protein
2. Fibrinogen (**may not be done routinely) |
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Term
| Sample requirements and handling |
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Definition
1. obtain blood from free-flowing vein
2. use a vacutainer to collect blood or fill Vacutainer after collection with needle/syringe (PROPER VACUTAINER is ESSENTIAL to avoid artifacts including RBC shrinkage and RBC morphology changes-especially echinocytosis crenation
3. Microtainers or microhematocrit tubes are available for very small volume (e.g. birds and neonates) |
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Term
| Sample requirements and handling (II) |
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Definition
4. Anticoagulants
5. Mix sample well to ensure proper anticoagulation (invert 20 times)-do not shake (mixing especially important in horses as RBCs settle rapidly
6. Make 2 blood smears immediately
7. Stains
8. Storage of blood
9. Laboratory evaluation of blood samples |
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Term
| Name three anticoagulants commonly used and describe them. |
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Definition
1. EDTA (purple top tube)-anticoagulant
-preserves cell detail
-mechnism: chelates Calcium
-causes hemolysis of some bird and reptile samples
2. Heparin (green top)-anticoagulant of choice for birds and reptiles
-less optimal WBC staining
-Mechanisms: binds and potentiates antithrombin III
3. Citrate (light blue top)-anticoagulant of choice for coagulation tests
-mechanisms: chelates calcium |
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Term
| Why should you make 2 blood smear immediately? |
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Definition
-anticoagulants can cause artifact in cell morphology if greater than 2 hours between blood collection and sample receipt in lab
2. blood storage results in cell degeneration adn pyknosis
3. dry the smears quickly to avoid drying artifact (e.g. refractile erythrocyte inclusions, and echinocytosis)
4. when submitting slides to outside lab, stain one to evaluate cellularty/quality however ALWAYS leave at least one smear unstained |
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Term
| Describe the different types of stains used for sample evaluation and correct staining technique. |
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Definition
1. stain smears within 2-3 days of preparation (time delay results in poor staining, bluish RBCs)
2. Romanowsky stains (Diff-Quik, Wright, Giemsa, etc.)
-stains composed of acidic and basic dyes
-staining requires alcohol fixation, buffering and staining
-acidic components stain blue (basophlic)-e.g. RNA
-basic components stain pink (eosinophilic)-e.g. Hb, proteins, eosinophil granules
-metachromatic substances stain purple (e.g. DNA and platelet, basophil and mast cell granules)
3. avoid contact of stains and smears with water |
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Term
| Describe the different types of stains used for sample evaluation and correct staining technique. (II) |
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Definition
4. formalin vapors cause a bluish hue to slides and DESTROY cytologic detail
by cross-linking cell proteins
-don't store formalin in same area as stains and smears
-don't package/ship formalin-fixed biopsy specimens for histopath submission with blood smears or cytologic smears!
5. New methylene blue
-aqueous rather than alcohol-based stain
-d/n fix cells and therefore is not permanent
-used in wet mounts, especially useful for eval of reticulocytes, Heinz bodies, mast cell granules, and fungal elements |
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Term
| Describe the proper technique for storage of blood: |
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Definition
1. Refrigerate whole blood if not analyzed within 2-3 hours (refrigerate while awaiting courier pickup)
2. samples can be refrigerated for 24 hours without alteration of quantitative RBC parameters
3. storage at room temp for >24 hours caused RBC swelling with subsequent increase in PCV, MCV, and decreased MCHC |
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Term
| Describe how laboratory evaluation of blood samples is conducted: |
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Definition
1. automated hematology analyzers are specifically designed, calibrated and validated for each vet spp, with each spp requiring different cell thresholds
-> thus, do NOT submit animal blood to human reference labs |
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Term
| Name the three parameters that assess RBC mass: |
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Definition
1.RBC count
2. Hemoglobin concentration (Hb)
3. PCV (or Hematocrit (HCT))
*All three parameters decrease in anemia and increase in erythrocytosis |
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Term
| What parameter is the most accurate measure of RBC mass and how is it measured? |
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Definition
| Hemoglobin concentration: directly measured using automated analyzers |
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Term
| Define PCV (packed cell volume) or hematocrit (HCT) (unit=%) |
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Definition
| -PCV is the percentage of RBC, by volume, in whole blood |
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Term
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Definition
-fill capillary tube with whole blood
-centrifuge at high speed for 3-5 minutes (separates cells by density)
-RBCs are more dense and get packed on the botto
-WBCs form a layer over RBCs (buffy coat) and platelets are found on top |
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Term
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Definition
| Calculated HCT= ((RBC count) X (MCV))/10 |
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Term
| How can PCV be falsely decreased or increased? |
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Definition
-decreased by inadequate filling of EDTA tube
-increased by prolonged blood storage |
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Term
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Definition
-unit= number X 10^6/ul
-requires an automated counter, manual counts are inaccurate |
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Term
| How can RBC be falsely decreased/increased? |
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Definition
-agglutination can falsely decrease RBC count
-hemolysis can falsely increase RBC (b/c RBC ghosts can be counted as RBCs by some analyzers |
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Term
| How is hemoglobin (Hb) measured and what are the units for Hb? |
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Definition
-units= g/dl
-measured spectrophotometrically following RBC lysis
-directly measured, very accurate |
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Term
| Describe what determines whether a RBC is mature and ready for release. |
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Definition
-Hb concentration within RBCs is what determines when a RBC is mature and ready for release from bone marrow
-cells with too much hemoglobin are not produced
-cells with too little hemoglobin are sometimes released |
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Term
| How can Hb be falsely increased? |
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Definition
-anything increasing turbidity increses absorbance and falsely increased Hb concentration (e.g. Heinz bodies, lipemia)
-Hemolysis falsely increases Hb |
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Term
| List the three RBC indices: |
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Definition
1. MCV (mean cell volume)
2. MCHC (mean cell hemoglobin concentration)
3. MCH=mean cell hemoglobin |
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Term
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Definition
-units=femtoliters
-MCB is directly measured by an analyzer
-MCV is a measure of cell size
-in anemia, RBCs can be small (decreased MCB, microcytic), large (increased MCV, macrocytic) or of normal size (normal MCV, normocytic) |
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Term
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Definition
-units=picograms
-MCHC=mean cell hemoglobin concentration (units=g/dL)
-MCH and MCHC are automatically calculated from HCT, RBC count, and Hb by the hematology analyzer
-both parameters describe "color" (b/c hemoglobin is pigmented and dictates cells color)
-MCH and MCHC essentially measure same thing
-in anemia, RBCs can have too little Hb relative ot cell size (decreased MCHC, hypochromic) or normal amount of hemoglobin in each cell (normal MCHC, normochronic)
-Note: increased MCHC ("hyperchromic") is almost always an artifact |
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Term
| True of false: any factors affected HCT, RBC, or Hb can affect indices (e.g. falsely increased MCV with agglutination or falsely decreased MCHC with hemolysis) |
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Definition
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Term
| Describe Red Cell Distribution Width: |
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Definition
-automatically determined by automated cell counters
-RDW=coefficient of variation of the red cell volume distribution |
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Term
| RCW is an index of:______________ |
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Definition
| the degree of anisocytosis or variation in RBC size |
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Term
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Definition
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Term
| True of false: Anemias with significant microcytosis, macrocytosis, or both will have increased RDWs. |
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Definition
True
-this may be an indicator of regeneration |
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Term
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Definition
-immature erythrocytes that contain residiual RNA and mitochondria
-correspond to polychromatophilic RBCs |
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Term
| Why are reticulocytes THE index of erythroid bone marrow regeneration? |
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Definition
| -reticulocytes are released prematurely from the bone marrow in response to anemia |
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Term
| How are reticulocyte counts reported? |
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Definition
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Term
| The Leukogram measures what? |
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Definition
| white blood cell (WBC) number |
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Term
| Which two methods are used to measure WBC number? |
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Definition
1. light-scatter
2. impedence |
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Term
| How are WBC counts performed and what is the unit for WBC counts? |
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Definition
-unit= number X 10^3/ uL
1. manual method (20% error)=> important for recognizing serial changes in a patient
2. automated counters have a 5% error (increases at very high and very low counts) |
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Term
| Do automated counters work well with avian and reptile WBC counts? |
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Definition
| -no, due to nucleated RBCs and thrombocytes (platelets) |
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Term
| What can falsely decrease/increase WBC counts? |
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Definition
-WBC clumping or WBC lysis will falsely decrease
-nucleated RBCs and clumped Heinz bodies or platelets may falsely increase WBC number on some analyzers |
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Term
| How is a differential WBC count performed and what does it measure? |
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Definition
-identifies which cell types comprise total WBC count
-in Vet Med generally performed by evaluating blood smear-> 100-200 WBCs are are identified and classified on blood smear exam.
-percent of each cell type (e.g. neutrophils, lymphocyte, monocyte, etc.) is used to determine the absolute number of each WBC type present per uL of blood |
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Term
| Can you use % to determine neutropenia/lymphopenia/eosinophlia, etc.? |
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Definition
| -NO, ONLY WBC numbers should be used |
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Term
| How is platelet count measured? |
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Definition
-plaetelet count (unit= number X 10^ 3 /ul)
-manual platelet counts can be performed using a WBC Unopette (25%) error
-automated count most common method of assessing platelet number (but still 10% error) |
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Term
| Which species are prone to platelet clumping, resulting in falsely decreased platelet counts? |
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Definition
| -cats, cows, mice and pigs |
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Term
| Where should you check smears for platelet clumps? What do platelet clumps indicate? |
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Definition
-along the feathered edge
-indicate adequate numbers of platelets |
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Term
| Why do automated counters have a difficult time distinguishing between platelets and RBCs? |
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Definition
| -Cats have small RBCs and relatively large platelets with marked variation in size, automated counters cannot always distinguish the two |
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Term
| How can difficult venipuncture affect platelety count? |
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Definition
| -results in release/expression of tissue-factor that can cause clotting or aggregation of platelets and decreased platelet count |
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Term
| EDTA my induce platelet clumping in which species (termed pseudothrombocytopenia)? What is recommended if this occurs? |
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Definition
-horses
-repeat platelet count with blood collected in sodium citrate |
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Term
| How is platelet size measured? |
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Definition
-mean platelet volume (MPV) (unit=femtoliters)
-measured value from hematology analyzer |
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Term
| What does increased MPV indicate? |
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Definition
-increased proportion of large platelets-> indicates bone marrow response to thrombocytopenia (i.e. immune-mediated thrombocytopenia)
-large platelets are released from the bone marrow during responsive thrombopoiesis |
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Term
| Why may an animal not show clinical bleeding even though platelet numbers are low (<25,000)? |
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Definition
| -large platelets are more reactive (increased granule density), thus if there are low numbers of platelets but the platelets are large, animals may not show clinical bleeding (i.e. bone marrow aspirations to evaluate megakaryocyte response to peripheral thrombocytopenia may be safe to perform with low numbers of hyperfunctional large platelets) |
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Term
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Definition
| Plasma is a cell-free, fluid component of anticoagulated blood. It contains abundant proteins, electrolytes, clotting factors and glucose (among other things) |
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Term
| What parameters of total plasma are measured in a CBC? |
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Definition
-total plasma "protein" and fibrinogen concentrations are only parameters measured
-plasma color is normally clear to colorless (dog and cat) to light yellow (cow and horse) |
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Term
| What color is icteric plasma? Hemoglobinemic? Lipemic? |
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Definition
-icteric: yellow and clear
-hemoglobinemic: pink to red and clear
-lipemia: whitish and opaque |
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Term
| How is total plasma protein concentration determined? |
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Definition
-using refractometry on plasma obtained after spinning down blood for a PCV
-serum protein on chem os deter,omed isomg a colorimetric biuret method that is VERY SPECIFIC for proteins |
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Term
| How acurate is TPP refractometry? |
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Definition
| -only an estimate of protien (refractometer measures anything in plasma that refracts light) |
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Term
| How can plasma protein readings be artificially increased? |
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Definition
| -abnormally high concentrations of glucose, urea, sodium, chloride, or lipid can artificially increase plasma protein and result in difference between plasma and serum protein concentrations |
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Term
| Plasma protein also contains fibrinogen and clotting factors that are consumed by clot formation. Do these contribute to SERUM protein? |
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Definition
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Term
| How is plasma fibrinogen concentration determined? |
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Definition
-using heat precipitation and refractometry
-estimate of true fibrinogen concetnration |
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Term
| What is increased fibrinogen and indicator of? |
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Definition
| -acute phase response and is particularly useful as an early indicator of inflammation in large animals |
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Term
| What is decreased fibrinogen an indicator of? |
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Definition
| -decreased fibrinogen can occur with consumptive conditions (e.g. DIC) |
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