Osmotic fragility test

The spherocytes are much more susceptible to osmotic lysis than are normal red blood cells. This is assessed in the osmotic fragility test, in which red blood cells are exposed in vitro to decreasing concentrations of NaCl. The physiologic concentration of NaCl is... 

The osmotic fragility test is the most sensitive and useful test for the diagnosis of HS (Fig. 6-2). Although the fresh red cells of about 20% of HS patients have a normal or near-normal osmotic fragility, the test performed in cells incubated at 37°C for 24 hours is more often positive in association with an increased rate of spontaneous hemolysis (autohemolysis). 

Figure 6-2. Osmotic fragility test (Parpart method). A typical osmotic fragility curve of fresh (left) or 24-hour incubated (right) erythrocytes from a patient with HS is shown. The hatched area represents the normal range.

Harada, R. Ito, Y. Kimura, E. A new method of osmotic fragility test of erythrocytes with coil planet centrifuge. Jpn. J. Physiol. 1969, 19, 306-314. 

Differential diagnosis of sphero-cytes in the peripheral blood includes warm AIHA (autoimmune hemolytic anemia) and hereditary spherocytosis. Use the osmotic fragility test (HS) and direct Coombs test (AIHA) to tell them apart. 

Hematological Methods. Hematological analyses can Include the determination of the total hemoglobin concentration (In g%), the packed cell volume (PCV In %), the red blood cell count (In 10 /mm ) and reticulocytes count (In %), calculation of the red cell Indices, examination of a blood film, tests to demonstrate the presence of Inclusion bodies and of sickle cells, tests to evaluate the distribution of fetal hemoglobin (Hb-F) Inside the red cells, the red cell osmotic fragility, the concentration of serum Iron (SI), total Iron binding capacity (TIBC), and the survival time of the red cells. Details of all... 

Dowell et al. reported an increase in the osmotic fragility of alveolar macrophage preparations obtained horn rabbits acutely exposed to ozone at 10 ppm for 3 h or intermittently exposed to ozone at 2 ppm for 8 h/day for 7 days. Similar intermittent exposure to ozone at 0.5 ppm was without effect. A test for malonaldehyde formation was negative, but this lipid peroxide breakdown product may have been lost during the preparatory procedure. 

The most important diagnostic features of HS are as follows (1) congenital hemolytic anemia (2) microspherocytosis on the peripheral blood film (3) increased osmotic fragility, particularly in incubated red cells and (4) negative antiglobulin (Coombs) test. 

Initial evaluation of novel biomaterial Tissue culture test on materials Tissue culture test on materials extracts Cell growth in contact with test materials Haemolytic activity test Intramuscular implantation of material Test of osmotic fragility of erythrocytes In vitro mutagenicity test... 

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