Diagnostic Specificity of Sucrose Hemolysis Test for Paroxysmal Nocturnal Hemoglobinuria

The diagnostic specificity of the various modifications of the sucrose hemolysis test for PNH was examined in detail. In whole blood screening tests the greatest specificity was achieved using citrated or oxalated blood and room temperature incubation (23°). Defibrinated whole blood should not be used since "false positive" hemolysis may occur in blood disorders other than PNH. Mechanisms were suggested for this phenomenon. The validity of the confirmatory sucrose hemolysis test employing normal serum was further reported. Because of the clear, colorless character of serum-sucrose mixtures, an insignificant degree of hemolysis (i.e., less than 5%) is more readily visible than in other PNH hemolytic tests employing undiluted serum. Definitive instructions and criteria for interpretation were given for both the whole blood screening test and the confirmatory sucrose hemolysis test.