OSMOTIC FRAGILITY TEST Flashcards
what is the principle behind the OFT
The osmotic fragility test is a measure of the ability of the red cells to take up fluid without lysing
The whole blood is added to varying concentrations of sodium chloride solution and allowed to incubate at room temperature. The rate of hemolysis is then determined through visual inspection of each saline concentration.
temperature we incubate the sample for oft
room temperature
what solution we are using for oft in which the blood we are testing is added?
sodium chloride solution
. The rate of hemolysis is then determined through CHEMICAL INSPECTION of each saline concentration.
True or false
false- visual inspection
the relative concentration of solutes dissolved in a solution which DETERMINE THE DIRECTION AND EXTENT OF DIFFUSION
tonicity
3 classification of tonicity
isotonic
hypotonic
hypertonic
a classification of tonicity in which
the solution has the same number of solute particles as the cell
isotonic
a classification of tonicity in which
the solution has fewer solute particles per liter of solution
hypotonic
a classification of tonicity in which
the solution with higher solute particles per liter of solution
hypertonic
a hypotonic solution will result to a __ of a cell
(swelling, shrinking)
swelling
a hypertonic solution will result to a __ of a cell
(swelling, shrinking)
shrinking
is a transport of water to a higher concentration of solute
osmosis
2 terms we need to consider in osmosis
concentration and tonicity
what is the difference between concentration and tonicity
tonicity - the difference of concentration into environment
concentration - the amount of solute
is the one responsible for the integrity and stability of the cell.
It as well controls the in and out of the cell.
plasma membrane
red cell with peripheral rim of hemoglobin surrounded by clear area and central hemoglobinized area
Target cell/Codocyte/Mexican hat cell
small, round, dense red blood cells with no central pallor
spherocytes
significance of OFT test
This test is employed to diagnose conditions in which the PHYSICAL PROPERTIES OF THE CELL ARE ALTERED
The _____ of the red blood cells is the primary factor affecting the osmotic fragility test
shape
OFT depends on which properties of rbc plasma membrane?
volume, surface area and functional state of the red blood cell membrane
. The larger the amount of surface area of the red cell membrane, the more fluid the cell is capable of absorbing before rupturing ( low OFT), and is usually observed in __ cells.
(target cell, spherocytes)
target cell
the spherocyte has the smallest surface area for its volume and ruptures more quickly which means it has (higher, lower) OFT
higher
diseases which we can found increase oft
hemolytic anemias and hereditary spherocytosis, older rbc.
decrease OFT are seen in what diseases
sickle cell anemia, iron-deficiency anemia, thalassemia, polycythemia and conditions where target cells are present, reticulocytes
materials used in OFT
- 12 test tubes
- Test tube rack
- 0.5% NaCl
- Distilled water
- Sahli pipette
- Heparinized blood
- Dropper
formula used in OFT
number of tube multiplied by the amount of blood (0.02 ml)
how many hours do we need to incubate the sample?
2 hrs - (we did it for only 1 hr)
how many minutes we do need to centrifuge the sample
5 mns
which tube do we need to start checking for initial hemolysis?
test tube #25
a stage where in a tinge of pinkness in the supernatant and some cells at the bottom of the tube are observed
initial hemolysis
a stage wherein clear, red supernatant with no microscopic cells at the bottom of the tube are observed
complete hemolysis
reference value or tube for initial hemolysis
0.42-0.44% (Test tube #21 or 22)
reference value or the number for complete hemolysis
0.32-0.34% (Test tube #16 or 17)
relationship of the test tube number and the hypotonicity of the solution
inversely proportional
