OFT

Question 1

What is the principle of osmotic fragility test?

Answer 1

The ability of red cells to take up fluid without lysing.

Question 2

Whole blodd is added to___and incubate at room temp

Answer 2

Sodium chloride

Question 3

What is tonicity?

Answer 3

Relative concentration of solutes dissolved in a solution which determines the direction and extent of diffusion.

Question 4

What isotonic solution?

Answer 4

A solution with the same number of solute particles.

Question 5

What happens to RBCs in a hypotonic solution?

Answer 5

RBC swells.

Question 6

What is hypertonic solution.

Answer 6

A solution with a higher solute particles.

Question 7

What happens to RBCs in a hypertonic solution?

Answer 7

RBC shrinks.

Question 8

What is a target cell?

Answer 8

A red cell with peripheral rim of hemoglobin surrounded by a clear and central hemoglobinized area (Bull’s Eye).

Question 9

It allows RBC to be flexible?

Answer 9

Central pallor

Question 10

What is the shape of target cells?

Answer 10

spherical/rounded

Question 11

What is spherocyte.

Answer 11

A small, round, dense red cell with no central pallor.

Question 12

What is the characteristic of spherocytes regarding flexibility?

Answer 12

They have no room for flexibility.

Question 13

Old cells have____ osmotic fragility?

Answer 13

High

Question 14

What is the purpose of the test?

Answer 14

To diagnose conditions in which the physical properties of RBCs are altered

Question 15

What factors primarily affects the Osmotic Fragility Test (OFT) (7)

Answer 15

-shape of RBC.
-Functional state of cell membrane.
-Clinical purity of sodium chloride.
-Accuracy of sodium chloride.
-Tonicity of solution.
-pH must be 7.4, a change of pH by 0.1 is equal to change of tonicity.
-surface area-to-volume

Question 16

Primary factor affecting OFT?

Answer 16

Shape of RBC

Question 17

_____the amount of surface area, more fluid the cell is capable of _______

Answer 17

Larger

absorbing before rupturing

Question 18

What is a spherocyte in surface area?

Answer 18

Decreased

Question 19

What is a target cell in surface area?

Answer 19

Increased

Question 20

What does a shift to the left indicate?

Answer 20

Increased OF

Question 21

What does a shift to the right indicate?

Answer 21

Decreased OF

Question 22

conditions associated with increased osmotic fragility. (3)

Answer 22

• Hemolytic anemias
• Hereditary spherocytosis
  *Older RBCs

Question 23

What is the required pH for the osmotic fragility test?

Answer 23

7.4

Question 24

How many test tubes are used in the procedure?

Answer 24

12 test tubes, numbered 14-25

Question 25

What is the concentration of NaCl used in the test tubes?

Answer 25

0.5% NaCl

Question 26

How many drops of 0.5% NaCl are added to the test tubes?

Answer 26

Same number of tube to the drops added

Question 27

What is the incubation time for the test tubes?

Answer 27

1-2 hours at room temperature

Question 28

How long should the centrifuge run?

Answer 28

5 minutes

Question 29

Which test tube is centrifuged first?

Answer 29

Test tube #25

Question 30

What indicates initial hemolysis?

Answer 30

Tinge of pinkness in the supernatant and some cells at the bottom of the tube

Question 31

What indicates complete hemolysis?

Answer 31

Clear, red supernatant with no microscopic cells at the bottom of the tube

Question 32

What is the reference value for initial hemolysis?

Answer 32

0.42 - 0.44% (Test tube #21 or 22)

Question 33

What is the reference value for complete hemolysis?

Answer 33

0.32 - 0.34% (Test tube #16 or 17)

Question 34

How do you compute the percentage of value?

Answer 34

Multiply the tube number to the 0.02

Question 35

What does a low numbered test tube indicate?

Answer 35

High hypotonic (more drops of distilled water)

Question 36

What happens if the first initial and complete hemolysis is LOWER?

Answer 36

Lower the OFT, increase capacity to swell in hypotonic solution

Question 37

What happens if the first initial and complete Hemolysis is HIGHER?

Answer 37

Higher the OFT, decrease capacity to swell in Hypotonic solution.

Question 38

High OFT is?

Answer 38

less fragile

Question 39

Low OFT is?

Answer 39

Fragile

Question 40

What happens if the OFT is lower than reference?

Answer 40

RBC doesn't get destroyed easily.

Question 41

What happens if the OFT is higher than the reference?

Answer 41

RBC gets destroyed easily.

Question 43

Conditions associated with decreased osmotic fragility. (5)

Answer 43

*sickle cell anemia *iron-deficiency anemia *polycythemia vera *thalassemia *reticulocyte