[Negative Ham's test and sugar water test on admission in paroxysmal nocturnal hemoglobinuria].

A 55-year-old man was admitted to our department because of shortness of breath and pancytopenia on March 27, 1992. On admission, palpebral conjuctiva were anemic. Laboratory findings showed pancytopenia, a reticulocyte count of 44,835/microliters, hemosiderinuria, LDH of 710 IU/l, haptoglobin of 6 mg/dl, NAP score of 301, red cell acetylcholinesterase of 1.5 U, negative Ham's test and negative sugar water test. Bone marrow was hypoplastic (2.4 x 10(4)/microliters). The erythrocytes of this patient showed complement-sensitive cells by the complement lysis sensitivity test, and a negative population consisting of double negative erythrocytes by flow cytometric two-color analysis using monoclonal antibodies to CD55 and CD59. A diagnosis of PNH with hypoplastic bone marrow was thus made. Therefore, flow cytometric two-color analysis appears to be superior to the standard tests currently used.