PAROXYSMAL NOCTURNAL HAEMOGLOBINURIA

Abstract

Abstract Case reports of eight patients with the PNH defect are presented.The diagnostic criteria applied are discussed: Ham's and Crosby's tests, the sucrose haemolysis test, acetylcholine esterase activity of the red cells, and signs of intravascular haemolysis with emphasis on the determination of lactate dehydrogenase activity in blood and bone marrow.The diversity of the presentation of PNH is outlined. One patient presented with attacks of abdominal pain for two years before diagnosis, three patients had longstanding pancytopenia with few clues to the diagnosis, two patients presented as cases of aplastic anaemia with initially negative Ham's tests, and two patients had concomitant myelofibrosis. The relationship of PNH to other blood diseases is discussed, and a possible connection with myelofibrosis is suggested. It thus appears that the PNH erythrocyte defect is encountered not only in the clinically classical PNH syndrome, but also in a variety of pancytopenias which are difficult to classify, and finally in some better defined conditions such as aplastic anaemia and myelofibrosis. This could be interpreted in several ways: 1. PNH is a nosological entity with an extremely wide clinical spectrum; 2. PNH is not a nosological entity, but erythroid cell lines carrying the PNH defect may be set up under many conditions when haemopoiesis is afflicted by a primary haematological disorder; 3. PNH exists (a) as a primary disorder, the clinically classical PNH syndrome, and (b) as a secondary defect in a variety of other haematological disorders. It is not yet possible to determine which of these possibilities, if any, is the right one, although at the present time the second interpretation would appear to be the most likely one.Clinical features are mentioned, particularly hypercoagulability and the occurrence of thromboses. An interesting aspect is that the majority of patients had an abnormal EEG. The significance of this remains to be determined. The multiple mechanism of anaemia in PNH is emphasized, including marrow hypoplasia, haemolysis, iron deficiency, autoimmunity, and folic acid deficiency.The value of blood transfusions, iron, adrenocorticoid and anabolic steroids in the management of PNH is discussed.