What is the normal range of osmotic fragility test?
With the technique of Parpart et al (1947), the normal range for osmotic fragility of red blood cells had been estimated to include 5%–45% haemolysis at a salt concentration corresponding to 4.5 g NaCl/l (Dacie 1954).
What does low value of osmotic fragility indicates?
After splenectomy the red cells are more homogeneous, the osmotic fragility curve indicating a more continuous spectrum of cells, from fragile to normal. Decreased osmotic fragility indicates the presence of unusually flattened red cells (leptocytes) in which the volume-to-surface area ratio is decreased.
What does the osmotic fragility test measure?
Osmotic fragility is a blood test to detect whether red blood cells are more likely to break down.
What is the fragility of red blood cells?
Erythrocyte fragility refers to the propensity of erythrocytes (red blood cells, RBC) to hemolyse (rupture) under stress.
What is the normal mean corpuscular fragility?
between 4 and 4.45 g/L NaCl
At times, the result of the osmotic fragility test may be expressed as the concentration of NaCl in solution that causes 50% hemolysis of erythrocytes. This is known as the median corpuscular fragility (MCF). For a normal sample of fresh blood, this is between 4 and 4.45 g/L NaCl.
Why decreased osmotic fragility in thalassemia?
Osmotic fragility is considered to be decreased if hemolysis is not complete in a 0.30% NaCl solution. Decreased osmotic fragility is associated with chronic liver disease, iron deficiency anemia, thalassemia, hyponatremia (Na < 130 meq/L), polycythemia vera, and sickle cell anemia after splenectomy.
What factors may affect the osmotic fragility test?
The extrinsic factors include the type, ionic strength and pH of incubation media, type of anticoagulant and storage time of the blood, ambient temperature, drugs, medicinal plant extracts, xenobiotics, chemical agents; whereas intrinsic factors are age, sex, breed, species, pregnancy, lactation and genetic factors.
What does increased osmotic fragility mean?
Spherocytic red blood cells have a decreased capacity to expand, and will rupture in mildly hypotonic conditions that fail to lyse normal red cells. They thus exhibit increased osmotic fragility. Osmotic fragility is determined by measuring the degree of hemolysis in hypotonic saline solution.
Why does osmotic fragility decrease in sickle cell anemia?
The decreased osmotic fragility of the erythrocytes in sickle cell anemia probably results from the cell damage which accompanies repeated sickle-unsickle cycles and which reaches its maximum in the irreversibly sickled cells.
When is osmotic fragility used?
The osmotic fragility test (OFT) is used to measure erythrocyte resistance to hemolysis while being exposed to varying levels of dilution of a saline solution. When erythrocytes are exposed to a hypotonic environment, water enters the cell and causes swelling and eventual lysis.
What causes increased osmotic fragility?
Although increased osmotic fragility is characteristically associated with hereditary spherocytosis, it may also be increased in other types of hemolytic anemia associated with the presence of spherocytes, particularly auto-immune hemolytic anemia, and in hypernatermia (Na > 155 meq/L).
What does a negative osmotic fragility test result mean?
An osmotic fragility test is often used to confirm red blood cell disorders. A normal test result is labeled as a negative result. Value ranges can be slightly different depending on when the laboratory the test was done, so if in doubt talk to a health professional about what the results mean.
What is the normal range for osmotic fragility of red blood cells?
With the technique of Parpart et al (1947), the normal range for osmotic fragility of red blood cells had been estimated to include 5%–45% haemolysis at a salt concentration corresponding to 4.5 g NaCl/l (Dacie 1954). This estimate may be questioned, however.
What is osmotic fragility test for spherocytosis?
Hereditary spherocytosis causes problems with the outer layer of your red blood cells, distorting their shape. This leads to more fragile red blood cells and early destruction, which can also cause anemia. For an osmotic fragility test, you’ll need to give a blood sample.
Can osmotic fragility test be used to confirm anemia?
However, sometimes the condition needs to be confirmed with other blood tests or genetic testing. This is because certain other conditions may also give similar results. The osmotic fragility test may also be used to help confirm if thalassemia or spherocytosis is the cause of anemia.