Hematocrit

hematocrit

percentage of red blood cells (RBCs) in your blood

• tells how much of your blood is made up of RBC

how to measure hematocrit

1. collect small blood sample

2. place blood in a thin capillary tube

3. spin tube in centrifuge to separate blood into layers (plasma, buffy coat, RBCs)

4. RBC’s layer’s height is compared to total blood height, making a percentage

what type of tube is blood put into?

capillary tube

what is used to separate the elements in the blood?

a centrifuge

what is the top layer of the tube?

plasma (mostly water and nutrients)

what is the middle layer of the tube?

buffy coat (wbc and platelets)

buffy coat

wbc and platelets

• middle layer of tube

what is the bottom layer of the tube?

rbcs

what is calculated to find the hematocrit %?

the RBC layer’s height is compared to the total blood height

normal hematocrit levels in men

40% to 54%

normal hematocrit levels in women

36% to 48%

how to use a hematocrit chart

1. After centrifuging, place the capillary tube on the hematocrit chart.

2. Align the bottom of the RBC column with the “0%” mark.

3. Align the top of the plasma with the “100%” mark.

4. The line where the top of the RBC layer falls gives the hematocrit value.

equipment needed for hematocrit

• Capillary tubes

• Centrifuge

• Microhematocrit reader (chart)

• Anticoagulated blood sample

• Gloves & PPE

positive control sample

contains a known hematocrit value within the normal range

importance of a positive control sample

tt ensures that the procedure and equipment are working correctly.

negative control

a sample with no RBCs (like just plasma) to check for errors or contamination

importance of negative control

to check for errors or contamination

blood doping

when athletes artificially increase their RBC count to get more oxygen to their muscles and improve endurance

why is blood doping dangerous?

too many RBCs make blood thicker, which increases the risk of blood clots, heart attacks, and strokes