hematology and oncology
Paroxysmal Nocturnal Hemoglobinuria (PNH)
Diagnosis of PNH
Flow cytometry Paroxysmal nocturnal hemoglobinuria is suspected in patients who have typical symptoms of anemia (eg, pallor, fatigue, dizziness, possible hypotension) or unexplained normocytic anemia with intravascular hemolysis, particularly if leukopenia or thrombocytopenia and/or thrombotic events are present. Historically, if PNH was suspected, the acid hemolysis (Ham test) or sugar-water test was usually the first test done. These tests relied on activation of complement via acidification of serum or high-concentration sucrose solutions. Currently, diagnosis of PNH is with flow cytometry, which is used to determine the absence of specific RBC or white blood cell surface proteins (CD59 and CD55). This test is highly sensitive and specific. Bone marrow examination is not necessary but, if done to exclude other disorders, usually shows erythroid hyperplasia. Gross hemoglobinuria is common during crises, and the urine will contain hemosiderin constantly. 