OFT Flashcards
Disadvantages of OFT
- Time consuming
- Lack sensitivity
- non-specific
Main factor of OFT
shape of erythrocyte
Shape of the erythrocyte depends on?
- volume
- surface area
- functional state of erythrocytic membrane
Whole blood + varying conc of NaCl
OFT
Solution where water molecules will pass in & out of the membrane in EQUAL AMOUNTS
Isotonic solution
What will happen to erythrocytes in HYPOTONIC solution?
- RBCs will hemolyze;
2. more water molecules enter THAN leave
It ruptures more quickly
Spherocytic erythrocyte
Characteristics of spherocytic rbcs (dec or inc/ easily lysed or not)
- easily lysed
- ↓ SA:V
- ↑ OFT
Have large surface area per volume
Target/sickle cells
Cells that can withstand osmotic pressure
Target/sickle cells
Is erythrocytic fragility inversely proportional to the rate of hemolysis or directly?
Directly proportional
Specimen used in OFT?
Heparinized Whole Blood/Fresh Defribinated Whole Blood
How many hours is the specimen in OFT stable at room temperature?
2
Stability hours of the specimen if refrigerated?
6
T/F: In each tube water enters & leaves RBC until equilibrium is reached
TRUE
- Absorbance 0
- Supernatant at tube 1
- 0% hemolysis
Spectrophotometer digital
- percentage transmittance %T
2. conversion table to read absorbance
Spectrophotometer conventional
Point where the tube with the highest concentration of NaCl
End point
Concentration where hemolysis should end
0.30% NaCl
T/F: Beginning hemolysis should NOT occur in a concentration >0.45%
TRUE
Test wherein you will know the type of cells that are easily ruptured
Osmotic Fragility Test
Initial & complete hemolysis of NORMAL OFT
I: 0.45%
C: 0.30%
Initial & complete hemolysis of HEREDITARY SPHEROCYTOSIS
I: 0.65&
C: 0.45%
T/F: Thalassemia & Sickle Cell Anemia DOES NOT have the same initial & complete hemolysis
FALSE; both have 0.35% (I) & 0.20% (C)
↑ OFT
Hereditary Spherocytosis
Acquired Hemolytic Anemia w/ Spherocytes
↓ OFT
Anemia w/ target cells
Curve shifted to the right
RBC ↓ OF
Initial hemolysis of NaCl = >0.5%
Curve shifted to the left
RBC ↑ OF
Incubating blood in 37C for 24hrs before OFT
Incubated OFT
It allows hereditary spherocytosis in a spherical shape
Incubated OFT
Test that demonstrates ↑ RBC fragility & RBCs have ↓ surface-area-tp-volume ratios
OFT
