Erythrocyte osmotic fragility test

Summary

This test is to determine the resistance of erythrocytes to different concentrations of hypotonic saline solution, this resistance is closely related to the ratio of surface area and volume of erythrocytes. If the surface area is large and the volume is small, the resistance to hypotonic saline is large (brittleness is reduced), and vice versa, the resistance is small (brittleness is increased), the surface area of spherical cells is deep/volume ratio is reduced, and the brittleness is increased. This experiment was obtained from the laboratory instruction of the 5-year testing program of Mudanjiang Medical College.

Operation method

Erythrocyte osmotic fragility test

Principle

This test is to determine the resistance of erythrocytes to different concentrations of hypotonic saline solution, this resistance is closely related to the ratio of surface area and volume of erythrocytes. Large surface area and small volume of the greater resistance to hypotonic saline (brittleness reduced) and vice versa, less resistance (brittleness increased), spherical cell surface area depth / volume ratio decreases, brittleness increases.

Materials and Instruments

NaCL solution Double-distilled water
Volumetric flask Test tube

Move

I. Experimental reagents: 17 mmol / L NaCI solution (10 g / L): take the 10O ℃ dried analytical NaCI 11.00O g volumetric flask, add appropriate amount of double-distilled water to dissolve, and then add double-distilled water to the scale.

l. Take 10g/L NaCI liquid and distilled water respectively, and add them into small test tubes according to the table;

2. Bring the test tube rack to the patient, use a dry sterilized syringe equipped with a No. 6 needle for intravenous blood of 1-1.5 ml, immediately drop in each tube, l drop in each tube, (2 drops can be added for anemic patients), and shake gently. Let it stand at room temperature.

3. Each test should be made at the same time normal control

II. Judgment of experimental results:

Prepare room temperature for 2 hours, observe the results, starting from the high concentration tube, the upper layer of the solution begins to appear transparent red color and the bottom of the tube with red blood cells is the beginning of lysis of blood vessels: the solution is transparent red color and the bottom of the tube is completely free of red blood cells is complete lysis of blood vessels.

Reference value: Start of hemolysis: 4.2-4.6g/L (71.8-78.6mmol/L).

Complete hemolysis: 3.2-3.4g/L (54.7-58.1mmol/L)

Patients with normal controls with a diagnostic value of 0.4 g/L of NaCl concentration associated with hemolysis.

Caveat

1. NaCl is dried at 10O C and stored in a desiccator, weighed accurately and prepared fresh before use.

2. Syringes and tubes must be clean and dry.

3. Anti-coagulation is contraindicated in this test; in special cases, heparin can be used for anticoagulation.

4. Observe under the milky white background to judge the complete hemolysis, if necessary, observe after centrifugation.

5. It is not easy to observe the beginning of hemolysis in patients with gangrene, and the red blood cells of patients with severe anemia are too few, all the red blood cells can be washed with isotonic saline and then formulated into 50% red blood cell suspension for the test.

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