Canterbury DHB
The main difficulty is to think of PNH as a cause of the patient’s presenting symptoms.
The peripheral blood may be pancytopenic or there may be a haemolytic anaemia. Iron deficiency may be present. The bone marrow may either show an erythroid hyperplasia or be hypoplastic. Evidence of dysplasia should be sought, and if present, bone marrow cytogenetics should be done.
The demonstration that CD55 and CD 59 are deficient on red cells by flow cytometry, is the diagnostic test. Ham’s acid lysis test is no longer done. Flow cytometry will also reveal the extent of the defect and reveal the proportion of PNH I, II, and III type cells (normal red cells are referred to as PNH1). Analysis of leucocytes can be done if the patient has been recently transfused.
Topic Code: 4937