RBC indices Flashcards

1
Q

Complete blood count is good for

A

Gives us a minimum set of values that are reliable and cost effective
Tests included in a CBC can be done with automated machines are manually

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2
Q

Complete blood counts includes

A

Total red blood cell count
Packed cell volume (PCV) or hematocrit
Plasma protein concentration (aka total protein-TP)
Total WBC count
Hemoglobin (Hb/Hgb) concentration
Erythrocyte indices
Blood film evaluation: differential count, morphology of WBC and RBC, platelet examination
These tests make up a hemogram
The total WBC count and differential count make up the leukogram

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3
Q

Packed cell volume (PCV) is what

A

Is is the percentage of whole blood made up of erythrocytes (RBCs)
This test can be used to evaluate the hydration status of the patient
It is also used to diagnose anemia or erythrocytosis

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4
Q

PCV is run as and is how accurate

A

This test can be run as a single test or as part of a CBC
This test is extremely accurate with an inherent error of ± 1%

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5
Q

How is PCV expressed

A

Hematocrit (Hct) or microhematocrit (mHct) is the PCV expressed as a volume
Ex. PCV= 42%, Hct= 0.42L/L

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6
Q

Sources of error in the PCV test

A

Failure to mix the blood sample properly
Hemolysis of the sample
Insufficient centrifugation time and/or speed which leads to incomplete packing of cells

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7
Q

Procedure for running a PCV*

A

Mix the blood gently- by gentle inversion of using a figure 8 motion
Fill two microhematocrit tubes about 75% full using capillary action
Hold tube horizontally until it is placed into the sealant, one end is inserted into the sealenat at least twice
Load the centrifuge by balancing the tubes, make sure the sealant end is towards the outer edge of the centrifuge
Follow the centrifuge instructions→ usually 2-5 minutes on the hematocrit setting
Turn the centrifuge on after securing the lid
Set timer (hematocrit setting)
Follow directions for the centrifuge
When the centrifuge stops, open it and examine the tubes
Once the sample has finished spinning, you can read the tubes
Requires two microhematocrit tubes to balance the centrifuge for quality control
Red ring on top will have heparin inside
Blue ring on top will not

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8
Q

How to read a PCV

A

Be sure to evaluate all three layers
The plasma layer- color and clarity
The buffy coat- width and color
The PCV- width

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9
Q

Yellow plasma in a PCV can indicate

A

Should be noted on the file, may be due to several problems
Liver disease
Hemolytic disorders
Nutrition supplements
Dehydration
Normal in plant and grain eaters (ruminants and poultry)
Due to carotenoids in the feed

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10
Q

Pink plasma in a PCV may indicate

A

Evidence of hemolysis
Usually due to poor collection or handling methods
May be due to intravascular disorders
Will affect other test results

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11
Q

White plasma can indicate

A

Lipedemia is due to the presence of fat in blood
Seen after eating
Rarely pathologic
Interdeers with many chemical tests

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12
Q

The middle layer in the PCV tube contains

A

(buffy coat)- contains the WBC & platelets, white appearance
It will appear red when there are significant numbers of nucleated RBCs present
The buffy coat
A normal buffy coat should be about the thickness of a dime (~1mm)

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13
Q

How do you read PCV

A

PCV is measured at the intersection of the top of the RBC mass and the buffy coat
Measured on a reader card
Results are in % and then converted to 0.XX L/L (always 2 decimal places)
Ex. PCV of 42%= Hct of 0.42L/L

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14
Q

Significance of PCV results

A

Used as a screening test for pathological conditions
Lower than normal values indicate anaemia
Can be falsely decreased if not enough blood was added to the blood tube
Diluted by anticoagulant
Higher than normal values indicate polycythemia or dehydration
Dehydration is more common
Make sure to mix you sample well immediately before filling the microhematocrit tubes

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15
Q

Normal PCV of canine

A

37-55%

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16
Q

Normal PCV of feline

A

30-45%

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17
Q

Normal PCV of equine

A

32-57%

18
Q

Normal PCV of bovine

A

24-42%

19
Q

Normal PCV of ovine

A

25-45%

20
Q

Normal PCV of coprine

A

21-38%

21
Q

Normal PCV of porcine

A

32-43%

22
Q

Plasma protein concentration tests for

A

This test will give an estimate of the total protein concentration of the two sample
It requies a refracometer and two spun michrohemtocit tunes

23
Q

How to perform a plasma protein concentration

A

After the PCV has been read, the tubes are carefully broken just above the buffy coat (within the plasma layer)
A few drops of plasma are placed on the prism of the refractometer
Let the plasma flow onto the refractometer, do not tap the tube on the crystal of the refractometer
Close the lid gently and look at the TP scale (it will be in g/100ml, an older refractometer it may be labelled as g/dL)
You will be reading the number on the scale at the light dark interface
Read on a refractometer

24
Q

Normal values for most species

A

50-80 g/L
Lipedemia and hemolysis will falsely elevate the results
g/dL=g/100mL
Must be converted to g/L with no decimal places
9 g/100 mL → 1000mL = 1L
9g/100ml X 1000mL/1L = 90g/L
9g/dL → 10dl= 1L
9g/1dL x 10dL/1L= 90g/L

25
Q

Hemoglobin is

A

Hemoglobin is the functional unit of the RBC
It carries oxygen to the tissue and CO2 to the lungs to be expired
Hemoglobin is made up of a heme portion containing iron (Fe) and the globin portion made up of paired amino acid chains

26
Q

How to measure hemoglobin

A

Hemoglobin test measure the quantity of hemoglobin per unit of blood volume
Automated analyzers
Some estimate hemoglobin content based on RBC count
Gives values for all forms of hemoglobin
Uses a lysing agent
Some dedicated hemoglobin analyzers only test for oxyhemoglobin and are very accurate when properly maintained
Can be calculated from the PCV
-PCV ÷ 3 = Hemoglobin in g/100mL
-Convert to g/L with no decimal places or exponents

27
Q

PDS hemoglobin guidelines

A

If the result is lower than 120 g/L in dogs or 80g/L in cats, then a reticulocyte stain should be evaluated

28
Q

Equine normal hemoglobin

A

110-180 g/L

29
Q

Bovine normal hemoglobin

A

80-140g/L

30
Q

Canine normal hemoglobin

A

120-200g/L

31
Q

Feline normal hemoglobin

A

110-160g/L

32
Q

Erythrocyte indices is

A

Also known as mean corpuscular values
Helpful for the classification of some types of anemia

33
Q

Erythrocyte indices includes

A

Mean corpuscular volume (MCV)
Mean corpuscular hemoglobin (MCH)
Mean corpuscular haemoglobin concentration (MCHC)

34
Q

How is erythrocyte indices calculated

A

by automated machine

35
Q

The following test must be performed to calculate the erythrocyte indices manually

A

PCV
Hgb (hemoglobin)
Total red blood cell count
Values obtained should always be compared to morphological features of the cells on the differential smear

36
Q

Mean corpuscular volume (MCV) determines what

A

Determines the average size of the individual red blood cells
(PCV÷RBC count)x 10= MCV in fL
Ex. PCV = 42%; RBC Count =6.0x 109/mL
(42÷6.0) x 10 = 70 fL
SI unit is femtoliters ( fL) (1fL= 10-15L)
Record your answer as a whole number

37
Q

Mean corpuscular hemoglobin (MCH) is and determines

A

Hemoglobin is what gives RBCs their coloration
Determines the mean weight of the Hgb in the average RBC
Measured in picograms (pg)
Calculation: Hgb ÷ RBC count

38
Q

Mean corpuscular hemoglobin concentration (MCHC) determines

A

Determines the concentration of Hgb in the average RBC
Ratio of the weight of hemoglobin to the volume in which it is contained
Expressed as g/L
Report as a whole number

39
Q

Normal range of MCHC in mammals

A

300–360g/L
Exception: Normal range for Camelidae and some sheep is 400-450g/L

40
Q

How to calculate MCHC

A

(Hgb g/L÷PCV %) x 100 = MCHC g/L

41
Q
A