Hematocrit Determination Quiz

What is the reference range for hematocrit in adult males?

Which component remains at the bottom of the tube after centrifugation of blood?

Which type of capillary tube is used for anticoagulated blood specimens?

What is the maximum duration recommended for centrifugation to achieve complete packing of RBCs?

What should be excluded when reading the hematocrit results?

What is a common effect of trapped plasma on microhematocrit results?

Which measurement of hematocrit typically considers RBC and MCV in its calculation?

What technical issue could affect the validity of the hematocrit measurement when using capillary tubes?

Hematocrit Determination

Hematocrit refers to the packed cell volume (PCV)
After centrifuging anticoagulated whole blood, red blood cells settle at the bottom
Packed cell volume is the volume of red blood cells
Reference ranges:
- Adult Males: 40% to 54%
- Adult Females: 35% to 49%
- Newborns: 53% to 65%
- SI Units: 0.40 to 0.54 L/L, 0.35 to 0.49 L/L, 0.53 to 0.65 L/L respectively
Micro-hematocrit tube:
- Approximately 75 mm long
- Inner bore: 1.2 mm
- Can hold 0.05 mL of blood
- Plug: 4 to 6 mm long
- Two types:
  - Red band/ring: for non-anticoagulated blood
  - Blue band/ring: for anticoagulated blood

Procedure

Perform skin puncture
Wipe off the first drop of blood
Fill two heparinized capillary tubes with blood
Seal the dry end with sealing clay and plug
Position tubes in centrifuge radial grooves
Spin at 10,000 RPM for 5 minutes
Read hematocrit (exclude buffy coat layer)

Additional Notes

Excessive anticoagulant leads to cell shrinkage
Air bubbles in the tubes do not affect results
Tubes are filled from opposite ends
Results should agree within 1% ± 0.01 L/L for two samples
Centrifuge at 10,000 g to 15,000 g to maximize red blood cell packing
Trapped plasma can elevate the microhematocrit reading (by 1% to 3%)
Automated hematocrit is a calculated value
Difference in hematocrit results is usually insignificant unless poikilocytosis or anisocytosis is present

Test your knowledge on hematocrit determination, packed cell volume, and reference ranges. This quiz will cover the procedures for collecting and centrifuging blood samples effectively. Understand the differences between anticoagulated and non-anticoagulated blood testing methods.