The Complete Blood Count

Clinical PathologyK. Canga, RVT

Reading and Assignments• Read pp: 32 – 38 (Start at CBC, end before histograms)• You MUST register at IDEXXLearningCenter.com and

complete the course titled: “The VetTest Certificate Course” RACE #106-11660

• This is FREE, and will count as 3 hours of CE to use after you become licensed.

• The course will take ~ 3 hours and you need to turn in a certificate of completion prior to using the IDEXX machines at school.

• Certificates are due by Monday, May 5. PLEASE print a hard copy. No Engrade or e-mail message will be accepted. (Yes, this is for points)

Composition of the CBC

• Total RBC count• PCV• Plasma Protein Concentration• Total WBC count• Blood film evaluation (differential WBC count, RBC

and WBC morphological evaluation, platelet estimation)

• Reticulocyte count• Hb Concentration• Erythrocyte indices (They’re baaack)

RBC Count

• Should be in the millions• Usually done by machine• Can be done manually with – Unopette and Hemacytometer– Is outdated and difficult to obtain diluents

PCV

• Packed Cell Volume• Indicates the percent of packed red cells in a

patient’s blood.• Done with hematocrit tube that has been

centrifuged• Takes VERY little time and can be quick

diagnostic tool• Normal ranges?

Plasma Protein Concentration

• Utilize the already centrifuged PCV tube• Read using a refractometer• Helps to determine abnormal amounts of

protein in blood– Protein present may be from fat, or other sources.– Normal Ranges?

Total WBC count

• Usually done by machine• Can be done manually with unopette and

hemacytometer method. (Again, outdated and difficult to obtain diluents)

• Critical in determining absolute number of WBCs. This is the number with diagnostic value.

Blood Film Analysis

• Used to calculate the relative WBC percentages

• Used to evaluate RBC and WBC morphologies• Used to perform reticulocyte count if patient

is anemic• Used to Perform platelet estimation.– REVIEW retic. and platelet calculations. I am not

going to re-teach these.

Calculating the Absolute WBC count

• You must have done a relative percentage from a blood film. (Written as a %)

• You must have a total WBC count• You will then take each relative percentage

and multiply each by the total WBC count from your CBC analyzed blood.

Calculating the Absolute WBC values

• Your relative percentages were as follows:– Neutrophils: 52%– Lymphocytes: 38%– Monocytes: 7%– Eosinophils: 3%– Basophils: 0%

• Take each cell’s percentage and multiply by the total WBC numbers from the machine readout. Let’s say that your total was 38,000.

Your WBC total was 38,000 • 38,000 x 52% = 19,760 total neutrophils• 38,000 x 38% = 14,440 total lymphocytes• 38,000 x 7% = 2,660 total monocytes• 38,000 x 3% = 1,140 total eosinophils• 38,000 x 0% = 0 total basophils• The % is VERY important in your calculation.

Simply hit the % key after you punch in the number you are multiplying the total by.

• NOTICE that your numbers add up to 38,000!

Hemoglobin concentration

• Usually done by machine• Different machines use different techniques to

estimate Hb concentration– Lysing solutions– Photometrics– Are only as accurate as machine is. Calibration is

important.

Erythrocyte Indices

• MCV: Average volume within RBC• MCHC: Average Hb concentration within RBC• MCH: Average weight of Hb within RBC– Review these calculations please!

Performing the CBC and Clinical Chemistry Tests on the IDEXX Machines

• Blood MUST be drawn in both Lithium-Heparin micro tube AND large purple top tube. (These are tubes designed for the IDEXX machines)

• You can use a serum separator tube in place of the lithium heparin tube.

• REMEMBER: – DO NOT remove the stopper from the large purple top

tube.– DO NOT fill tube past bottom of label (0.5 – 1.5 cc)– You WILL need to remove the top from the micro-tube.

IDEXX CBC and Chemistry• Centrifuge the microtube or serum separator

tube for ~7 minutes.• Transfer plasma or serum off and place in

serum cup. (Barbie shot glass)• Place purple top tube and grey top tube

obtained from Ms. Kenner in CBC machine.• Bar codes on purple and grey tubes MUST

MATCH in order for your tests to be valid. (If purple tubes do not have a bar code, this is OK, as long as they’re the large tubes!)

IDEXX Machines

• To run the chemistry portion of the test, you will obtain test slides from Ms. Kenner

• On the Monitor of the VetLab Station, use the stylet to enter the following information:– Click “Analyze Sample”– Enter Client: “VTI”– Enter P. Name: Patient id # is fine– Select next and then select reason: “Routine SX/Wellness”– At the bottom of the screen, you will need to tap the test

icons desired. (CBC and Chemistry) and THEN

– STOP

Running your Tests

• If you haven’t already loaded the large purple top and grey top tubes in to the CBC machine, do so now. Then hit RUN

• Look at the LED screen on the body of the Vet Test Machine.

• Follow prompts on the LED screen. – This is where you will add the slides ONE AT A TIME. (DO

NOT OPEN the foil until you are ready to load the slide in to the machine.)

– DO NOT touch the center of the slides. You will need to handle the slides by the edges and make sure the bar code is UP

Running your Tests• Once you have placed all the slides in the machine,

follow the prompts on the LED screen.• Place pipette tip securely on the pipettor of machine.• Press “E” on LED keyboard to continue the analysis.• lower pipette into plasma and press button. Machine

will beep 1 time. (Release button)• 2 beeps: Remove pipette• 3 beeps: wipe pipette tip and replace in machine

within 20 seconds. You will hear one more beep after pipette is replaced.

Test is Running

• The machine will automatically pipette the appropriate amount of plasma on each slide to run the tests.

• Total run time is ~6 minutes• When test is complete, press E• Remove pipette tip, empty used slide drawer • Machine should start printing results. If not,

press E and wait. If results are still not printing, try selecting option 2: print results.

Printers

• The internal printer on the IDEXX machine is disabled on our machine.

• We have an external printer connected to print results.

• PAPER MUST BE LOADED before you start running tests.