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Blood
Laboratory |
Red cell fragility
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Procedure, continued |
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At this point, a calibration curve must
be generated. Knowing that 0% hemolysis has occurred in tube #1 (isotonic solution) and
that 100% hemolysis has occurred in tube #6 (distilled water), we can plot the linear
relationship between % hemolysis and O.D. |
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You must now
determine the %hemolysis for each tube from the calibration curve.
Enter OD values below and get the corresponding % hemolysis from
the Calibration Curve. |
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You also need to
calculate the osmolarity of each solution in order to later on plot
the % hemolysis versus the osmolarity.
How do I calculate osmolarity?
1M solution of NaCl: 58.5 g/L
0.9 g% NaCl corresponds to 9 g/L of NaCl |
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The
Osmotic Fragility Curve
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Given the following
OD values and your calculated osmolarity and % hemolysis for test
tubes #1 to #6, how would you draw the osmotic fragility curve?.
Try to trace it in the area to the left (your trace will appear
blue). Once you are done, click on the "Done" button,
and the correct answer will be displayed in a new window.
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Tube
#
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NaCl
g/100ml |
OD
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%Hemolysis |
Osmolarity
(Osmols/l) |
| 1 |
0.9 |
0 |
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| 2 |
0.6 |
0.05 |
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| 3 |
0.5 |
0.45 |
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| 4 |
0.4 |
0.48 |
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| 5 |
0.3 |
0.49 |
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| 6 |
0.0 |
0.5 |
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The osmotic fragility test is designed to
give some information on the capacity of the red cell membrane to
withstand increasing internal pressures brought about by the diffusion
of water into the cell.
Questions to think about:
- what would be the significance of a
shift to the right- or to the left- of the osmotic fragility curve?
- how would the shape of the
erythrocyte (sickle cells vs. normal erythrocytes), its surface area
to volume ratio (biconcave shape vs. spherocyte) shift the osmotic
fragility curve?
To continue with
the next section, ESR, click here |
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