Podcast
Questions and Answers
What is the principle behind the microhematocrit method for determining hematocrit?
What is the principle behind the microhematocrit method for determining hematocrit?
- Analyzing blood using a colorimeter
- Measuring blood pressure in capillaries
- Mixing blood with anticoagulants
- Spinning a blood-filled capillary tube in a centrifuge (correct)
Which of the following conditions can lead to an increased hematocrit result?
Which of the following conditions can lead to an increased hematocrit result?
- High altitudes (correct)
- Pregnancy
- Dehydration (correct)
- Anemia
Which instrument is used in the microhematocrit method to measure packed cell volume?
Which instrument is used in the microhematocrit method to measure packed cell volume?
- Centrifuge scale
- Hemoglobinometer
- Microhematocrit reader (correct)
- Blood pressure monitor
What is the recommended RPM and time setting for centrifuging the capillary tubes in the microhematocrit method?
What is the recommended RPM and time setting for centrifuging the capillary tubes in the microhematocrit method?
Which step is crucial to avoid falsely low hematocrit results in the microhematocrit method?
Which step is crucial to avoid falsely low hematocrit results in the microhematocrit method?
What is the expected hematocrit reading when the bottom margin of the red cell layer is against the O mark?
What is the expected hematocrit reading when the bottom margin of the red cell layer is against the O mark?
Which materials are required for performing the microhematocrit method?
Which materials are required for performing the microhematocrit method?
What common misconception might lead a student to incorrectly conduct the microhematocrit test?
What common misconception might lead a student to incorrectly conduct the microhematocrit test?
Study Notes
Hematocrit Overview
- Hematocrit (Packed Cell Volume, PCV) measures the proportion of blood volume occupied by red blood cells.
- Determined through two methods: macro-method (Wintrobe's) and micro-method (microhematocrit).
Microhematocrit Method
- Principle: Blood-filled capillary tubes are spun in a centrifuge to separate components.
- Hematocrit measurement can also be obtained via Coulter counter analyzers.
Required Materials
- Capillary tubes (75 mm, plain)
- Microhematocrit centrifuge
- Microhematocrit reader
- Hematocrit tube sealant (e.g., plasticine, sealing wax)
Procedure for Sample Collection
- Use capillary or venous blood collected in an anticoagulated EDTA tube, or directly collected blood.
Step-by-Step Procedure
- Gently mix the blood 5 times to ensure uniformity.
- Fill capillary tubes to 2/3 full with blood, ideally using two tubes per sample.
- Seal one end of each tube and place them in the centrifuge.
- Centrifuge at 10,000 rpm for 5 minutes to separate the blood components.
- Insert the tube into the microhematocrit scale/reader for measurement.
- Align the scale so the bottom margin of red cell layer meets the O mark, and the top margin of plasma layer meets the 100 mark.
- Adjust the sliding line to accurately cut between the red cell layer and the buffy coat.
- Record the reading as the PCV percentage.
Conditions Affecting Results
- Decrease in hematocrit may indicate:
- Anemia
- Pregnancy
- Increase in hematocrit may be seen in:
- Newborns
- Burn patients
- Individuals at high altitudes
- Dehydration
Normal Values/Range
- Standard hematocrit values vary but specific ranges are not detailed in the notes.
Precautions
- Ensure complete sealing of capillary tubes to prevent falsely low hematocrit results.
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Description
This quiz explores the principles and methods of hematocrit measurement, focusing on the macro-method, specifically Wintrobe's method, and the micro-method using a microhematocrit centrifuge. It discusses the necessary materials and instruments involved in these techniques.
