Norm of Sucrose Hemolysis Test
<5% hemolysis, or negative.
Usage of Sucrose Hemolysis Test
Screening for paroxysmal nocturnal hemoglobinuria (PNH).
Description of Sucrose Hemolysis Test
Paroxysmal nocturnal hemoglobinuria is an acquired anemia characterized by the production of abnormal hemopoietic cells, red blood cells with an abnormal sensitivity to complement, and erythrocyte hemolysis. Symptoms include leukopenia or thrombocytopenia as well as nocturnal hemoglobinuria, chronic anemia, and thrombosis. Symptom severity is related to the degree of red blood cell sensitivity to complement and varies from client to client. In this test, sucrose provides a medium of low ionic strength that promotes the binding of complement to red blood cells. Blood from clients with PNH demonstrates the results of excessive lysis.
Professional Considerations of Sucrose Hemolysis Test
Consent form NOT required.
- Tube: Blue topped.
- Specimens should NOT be drawn during hemodialysis.
- Draw a 5-mL blood sample.
- Mix the washed red blood cells with ABO-compatible normal serum and 10% isotonic sucrose.
- Incubate the tube 30 minutes at room temperature.
- Centrifuge the tube.
- Read the percentage of hemolysis that results.
Client and Family Teaching
- Results are normally available within 2 hours of the test.
Factors That Affect Results
- Hemolysis or clotting of the specimen invalidates the results.
- False-positive results occur with megaloblastic anemia, autoimmune hemolytic anemias, dyserythropoietic anemia, lymphoma, adenocarcinoma of the colon, eosinophilia, renal failure, or bronchogenic carcinoma.
- False-negative results may occur in clients who have received recent blood transfusions or if the specimen has been collected in a lavender-topped tube containing EDTA or a green-topped tube containing heparin.
- Recent advances in the diagnosis of PNH include direct identification of affected cells by flow cytometry, detection of impaired synthesis of GPI anchor, and cytogenic analysis of the abnormal expression of the PIG-A gene.