sucrose hemolysis test
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Indications
- whenever paroxysmal nocturnal hemoglobinuria (PNH) is in the differential diagnosis
- any hemolytic anemia of obscure origin
Principle
Sucrose provides a medium of low ionic strength that promotes binding of complement to erythrocytes. In PNH, a population of the red blood cells (RBC) are abnormally sensitive to complement- mediated lysis.
Procedure
The patients washed RBC's are mixed with ABO-compatible serum & isotonic (10%) sucrose. This is incubated at room temperature for 30 minutes, then centrifuged. The % hemolysis in the supernatant is determined. Two control tubes: one omitting serum, the other omitting the RBC should be negative.
Interpretation
- <5 % hemolysis is a negative test
- >10 % is diagnostic for PNH
- 5-10% may be seen in megaloblastic anemia & AIHA
- False negatives result if serum lacks complement activity
More general terms
References
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 635
- ↑ Sugar Water Test Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0049005.jsp