Blood Count Flashcards
What does full blood count mean?
Refers to a panel of tests used to determine whether haematological abnormalities are present
What are the essential measurements in a full blood count? (3)
Red cells
Platelets
White cells
When doing a full blood count what must be added?
Why?
EDTA
Chelates Ca2+ - acting as an anticoagulant
So the sample doesn’t clot
What is devise is used for full blood counts?
Main reason why?
Automated analysers
Can sample hundreds of samples in a day
What type of system are analysers?
Closed system
What are the different analyser techniques? (2)
Flow cytometry
Spectrophotometry
Describe spectrophotometry *****
- Hypotonic solution lyses cells
Amount of light absorbed by sample proportional to amount of absorbent compound
Describe flow cytometry
- Single file line of cells
- Light beam or electrical current passed through
Scatter=size
More scatter=bigger cell
Why does it not matter if WBC are also counted when counting RBC?
They are so few in number
Wont significantly affect RBC
What is haematocrit?
The proportion of the blood that is made up of RBC
Describe how would you measure the packaged cell volume?
Centrifugation
Allows visitation - can compare the height of the red cell fraction with the height of total blood
Why is the packed cell volume no longer used to measure haematocrit?
What has it been replaced by?
Too slow - not compatible with high throughput in analysis labs
Calculation of mean cell volume of red cell x number of red cells per l
