Hematology / CBC / HM5

Question 1

Causes of Hemolysis

Answer 1

• Too much pressure / suction
• Too small of a needle
• Too much alcohol
• Fishing for the Vein
• Not removing needle when transferring to collection tube

Question 2

Tube Fill Order

Answer 2

Citrate - Coagulation (VSPro)
No Additive - Chemistry (VS2)
Lithium Heparin - Chemistry (VS2)
EDTA - Hematology (HM5)

Question 3

EDTA Contamination

Answer 3

• Spurious hypocalcemia (Ca2)
• Spurious hyperkalemia (K+)

Decreased calcium, increased potassium
(Too many bananas, not enough milk!)

Question 4

Citrate Contamination

Answer 4

Decreased calcium without an effect on potassium

Question 5

What Kind of Technology in the HM5

Answer 5

Impedance

Question 6

How to HM5 Measures Blood (Process through the machine)

Answer 6

Blood -> 
Dilution 1 (EOS) -> 
Dilution 2 (WBC / *HGB; uses spectrophotometry) 
Dilution 3 (RBC / MCV / PLT / MPV )

MCHC and HCT Are Calculation from Measured Parameters

Question 7

Dilution Process

Answer 7

ETA Whole Blood (25ul) - >
Direct EOS Count (Dilute 1:160 with species dependent volume of lyse2, this destroys all cells but EOS)
Clean / Rinse Cycle
ETA Whole Blood (25ul) - >
Diluted 1:160
- Mixed with lyse 1:180 to measure WBC and HGB
- Mixed with Dilutent 1:32000 to measure RBC and PLT

Question 8

ul

Answer 8

Microliter

Question 9

Lyse

Answer 9

Causes Hemolysis

Lyse2 is a Dilute and Hemoltic Agent

Question 10

Key Components of the HM5

Answer 10

Chamber - Mixing / Diluting of Blood
Aperture - Microscopic hole that carries and electric potential field across it (cells travel through this hole)
Measuring Tube - contains aperture; counting and sizing of cells happens here
Electrodes - one on either side fo the apeture to set up the apeture

Question 11

HM5 Chamber

Answer 11

“Counting Chamber” - Mixing and diluting of the blood occurs here

Question 12

Aperture

Answer 12

Microscopic hole that carries an electric potential field across it; cells travel from the counting chamber through this hole

Question 13

Measuring Tube

Answer 13

Where cells are counted and sized after passing through the aperture

Question 14

Electrodes

Answer 14

On either side of the aperture, sets up a electric field across the aperture

Question 15

Impedance Technology

Answer 15

• Blood is diluted with and isotonic solution to conduct a current
• Aperture has electrodes on either side; causes isotonic solution to conduct electricity and allows a voltage to be measured on the aperture
• Neutral cells pass through the aperture and emit a voltage based on their size
• when a cell is passing the aperture a small change in electrical impedance causes voltage rise and produces rise and electrical pulse. The bigger the size of the cell, the higher the pulse.

Question 16

Photometry

Spectrophotometry

Answer 16

Measures Hemoglobin HBG

• passing light through WBC dilution and measuring transmitted light with a photo detector
• the light intensity is logrithmically proportinal to concentration of hemoglobin
• Standard across veterinary CDC analyzers and is very accurate

HGB = 1/3 of HCT ; this can be used as a quality assurance tool. Abnormalities like heinz bodies can affect the HGB reading.

Question 17

HCT % (Hematocrit)

Answer 17

Calculated Value 
(RBC x MCV) / 10  [Wintrobe Index] 

Sources of error

• Delay before analysis
• Sample not mixed adequately

Question 18

PCV (Packed Volume)

Answer 18

What percentage of blood is made my red blood cells

Question 19

Calculated Parameters in the HM5

Answer 19

• HCT

- MCHC

Question 20

MCV Issues

Answer 20

Mean Cell Volume

Falsely increased due to delays in anaysis over time (RBC can undergo in vitro swelling)
Falsely decreased in too much EDTA and not enough blood
- EDTA is hypertonic and shrinks cells)

This will afect our HCT value

Question 21

MCHC

Answer 21

Mean Corpuscular Hemoglobin Concentration
[Mean concentration of HGB per RBC)
(HGB / HCT) x100

Anything that increases HGB or decreases HCT will falsely increase MCHC

• increased; almost always an artifact (very rarely oxidative damage)
• decreased; hemolysis or low blood/EDTA ratio

Question 22

Causes for Increased MCHC

Answer 22

• Lipemia and ictreis due to spectral interferance
• Under filled EDTA tube (increased EDTA to Sample Ration; decreases MCV and HCT which affect MCHC)
• Heinz Bodies cause incomplete RBC lysis and affect RBC
• Nucleated RBC
• Oxyglobin

Question 23

Histrograms (Brief)

Answer 23

Graphical representation for cell distribution and cell counts

• Verify Parameters
• ID uncommon DZ processes
• Provides quality control

Question 24

Thrombocytes =

Answer 24

Plateles

Question 25

Elements of a Histrogram

Answer 25

X - Axis (Horizontal) = Size of cells (increase from left to right) Measured in femtoliters Y - Axis (Vertical) = Relative cell count, scaled according ot highest calue on histrogram, cannot compare peak heights among samples / run Discriminator Bars = Run vertically, separate different cell types

Question 26

Cell Size Order (small to large)

Answer 26

``` Plateles RBC Lymphocytes Granulocytes Monocytes ```

Question 27

What 4 Histograms Appear

Answer 27

Platelet

Question 28

Platelet Histogram

Answer 28

PLT: smallest cells, prone to clumping Typical curve looks like a Ski Slope (majority smaller in size with fewer large sizes PLTS) Needs to trend upward and then back downward Cat peak may not finish at the bottom of the Y Axis A squiggly curve may indicate platelet clumping

Question 29

Platelet Clumping on Histogram

Answer 29

- Squiggly line on platelet histogram instead of the ski slope curve - Decreased platelet - Increased MPV