Week 9 Lab: OFT

Question 1

Method used for Osmotic Fragility Test?

Answer 1

Griffin and Sanford method

Question 2

The osmotic fragility test is a measure of the ability of the red cells to?

Answer 2

take up fluid without lysing

Question 3

In OFT, whole blood is added to varying concentrations of __________ and allowed to incubate at room temperature.

Answer 3

sodium chloride solution

Question 4

In OFT, whole blood is added to varying concentrations of sodium chloride solution and allowed to incubate at what temperature?

Answer 4

room temperature

Question 5

The rate of hemolysis is then determined through?

Answer 5

visual inspection of each saline concentration

Question 6

the relative concentration of solutes dissolved in a solution which determine the direction and extent of diffusion

Answer 6

Tonicity

Question 7

solution with the same number of solute particles as the cell

Answer 7

Isotonic

Question 8

solution with fewer solute particles per liter of solution

Answer 8

Hypotonic

Question 9

solution with higher solute particles per liter of solution

Answer 9

Hypertonic

Question 10

Hypotonic solution causes RBCs to?

Answer 10

swell

Question 11

Hypertonic solution causes RBCs to?

Answer 11

shrink

Question 12

a red cell with a peripheral rim of hemoglobin surrounded by clear area and central hemoglobinized area (bull’s eye)

Answer 12

Target cell/Codocyte/Mexican hat cell

Question 13

small, round, dense red blood cells with no central pallor

Answer 13

Spherocyte

Question 14

This test is employed to diagnose conditions in which the physical properties of red blood cells are altered.

Answer 14

Osmotic Fragility Test

Question 15

the primary factor affecting the osmotic fragility test

Answer 15

shape of the red blood cells

Question 16

the shape of the red blood cells depends on?

Answer 16

the volume, surface area, and functional state of the red blood cell membrane

Question 17

The larger the amount of surface area of the red cell membrane, the more fluid the cell is capable of absorbing before rupturing (thus, ____ OFT), and is usually observed in target cells.

Answer 17

decreased OFT

Question 18

As the red cell takes in fluid, it becomes rounder. It therefore follows that the spherocyte has the smallest surface area for its volume and ruptures more quickly (thus, ____ OFT).

Answer 18

increased OFT

Question 19

Increased osmotic fragility is found in?

Answer 19

• hemolytic anemias
• hereditary spherocytosis

Question 20

Decreased osmotic fragility is seen in?

Answer 20

• sickle cell anemia
• iron-deficiency anemia
• thalassemia
• polycythemia
• conditions where target cells are present

Question 21

Materials for Osmotic Fragility Test?

Answer 21

• 12 test tubes
• Test tube rack
• 0.5% NaCl
• Distilled water
• Sahli pipette
• Heparinized blood
• Dropper

Question 22

Why do we use heparinized blood for OFT?

Answer 22

Heparinized blood or defibrinated blood is preferred for osmotic fragility test because of the absence of “salts”. EDTA, oxalates or sodium citrate will increase the “salt” concentration of blood and possibly skew the results.

Question 23

Concentration of NaCl used for OFT?

Answer 23

0.5% NaCl

Question 24

gtts means?

Answer 24

drops

Question 25

Amount of blood placed in each test tube for OFT?

Answer 25

20 uL (0.02 mL)

Question 26

In OFT, incubate the test tubes at ______ temperature for ______.

Answer 26

room temperature; 2 hours (pero nung experiment, 45 minutes lang)

Question 27

Centrifugation time after the tubes have been incubated in OFT?

Answer 27

5 minutes

Question 28

Starting from test tube #_____, identify the test tube number where the first initial and complete hemolysis was observed.

Answer 28

25

Question 29

Initial hemolysis description?

Answer 29

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

Question 30

Complete hemolysis description?

Answer 30

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

Question 31

Reference value for initial hemolysis?

Answer 31

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

Question 32

Reference value for complete hemolysis?

Answer 32

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

Question 33

How to get the value in percent?

Answer 33

multiply the number of the tube with initial and complete hemolysis by 0.02 (the amount of blood delivered in each test tube)

Question 34

Decreased OFT correlations?

Answer 34

• sickle cell anemia
• iron-deficiency anemia
• thalassemia
• polycythemia vera
• conditions where target cells are present
• reticulocytes

Question 35

Increased OFT correlations?

Answer 35

• hereditary spherocytosis
• conditions where spherocytes are present
• older RBCs

Question 36

decrease in tube number means?

Answer 36

more hypotonic (more drops of distilled H2O than drops of NaCl)

Question 37

Test tube # with first initial and complete hemolysis is LOWER than reference means?

Answer 37

Lower the OFT (increase capacity to swell in hypotonic solution)

Question 38

Lower OFT implies?

Answer 38

RBC doesn’t get destroyed easily, and can resist lysis even in hypotonic solutions

Question 39

Test tube # with first initial and complete hemolysis is HIGHER than reference means?

Answer 39

Higher the OFT (decrease capacity to swell in hypotonic solution)

Question 40

Higher OFT implies?

Answer 40

RBC gets destroyed easily, and gets lysed even when exposed to isotonic solution