Investigation:  Hematocrit

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A hematocrit test measures the proportion of red blood cells in a sample of blood.  The normal percentage is 42-54% for males, and 38-46% for females.    To determine the percentage, a sample of blood is placed in a capillary tube and then centrifuged.  This causes the red blood cells to separate and sink to the bottom.  In labs, the hematocrit is measured by a machine that determines a variety of tests, called a CBC, Complete Blood Count.

For each patient sample shown, use a ruler to measure the total volume in millimeters, the RBC volume and then calculate the hematocrit.  


  patient 1 patient 2 patient 3 patient 4
 

Patient 1

Patient 2

Patient 3

Patient 4

RBC



     

Total Volume

     

Hematocrit (%)



     

 

Part 2:  Analyze and Diagnosis Patient Samples

1. Obtain 3 patient samples that show (simulated) blood in a test tube.   

2.  In order to separate the mixture, you will need to place the test tubes in a centrifuge.  Your instructor will show you how to operate the equipment.    (Alternatively, you can let samples sit for 10 minutes and blood cells will separate. )

3.  Use the marks on the test tube to determine the hematocrit for each sample.  (See formula)

4.  Complete data table:

 

Patient 1:  Ann Emia (F)

Patient 2: Juan Dice (M)

Patient 3: Laren Gitis (F)

Volume of RBCs

    

 

 

Total Volume

    

 

 

Hematocrit (%)

    

 

 

Diagnosis (high, low, normal)

    

 

 

Discussion

1.  How can hematocrit be used to diagnose a condition like anema?

2. Polycythemia is a condition where hematocrit numbers are high.  High levels make the blood thicker, which can result in strokes, blood clots, and heart attack.  Which patient is most at risk for these complications?   What chemical produced by basophils thins the blood?  What drug is often used as a blood thinner?  (You may need to look these up.)

3. The spleen is responsible for removing old and damaged blood cells.  A condition called splenomegaly occurs when the spleen must work harder.  Suggest a reason why a person with a high hematocrit might suffer from splenomegaly.

4.  Erythropoietin (EPO) is a hormone that stimulates the production of red blood cells.  It has also been used by athletes to give them an advantage.  How could a  hematocrit test be used to determine if an athlete was abusing EPO?

Teacher Notes:

To make hematocrit samples, use graduated test tubes and fill with red sanding sugar (the kind used in baking) to simulate red blood cells.  Fill the rest of the test tube with vegetable oil.  The recipes shown below do not have to be perfect

Recipes:  

Ann Emia         2-3 ml of sugar  fill to 10 ml mark with vegetable oil  (low hematocrit, anemia)
Jaun Dice         5 ml of sugar   + 5 ml of oil (normal for male)
Laren Gitis        5-6 ml of sugar   (high for female, polycythemia)