Haemolytic anaemia characterised by evidence of intravascular haemolysis such as haemoglobinuria and elevation of plasma lactate dehydrogenase.
Diagnosed by flow cytometry of granulocytes and red blood cells, looking for the lack of the glycosylphosphatidylinositol anchor or of proteins dependent on it for attachment to the cell membrane.
Complicated by thrombosis, particularly of hepatic and other intra-abdominal veins, cerebral veins, and other usual and unusual venous sites.
Specifically treated with a monoclonal antibody to the fifth component of complement (eculizumab).
Related to aplastic anaemia in that it may arise in patients with or recovering from aplastic anaemia, and it may manifest with cytopoenias that are the result of marrow hypoproduction, which may respond to treatment for aplastic anaemia.
Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired disorder of the blood characterised by intravascular haemolysis and thrombophilia due to the absence of glycosylphosphatidylinositol-anchored proteins on the membrane surface of blood cells.   It is associated with relative or absolute marrow hypoplasia.
Associate Professor of Clinical Medicine
Jane Anne Nohl Division of Hematology
Keck-USC School of Medicine
ICW receives speaker honoraria from and undertakes consultancy for Alexion Pharmaceuticals.
Dr Ilene Ceil Weitz would like to gratefully acknowledge Dr Wendell F. Rosse, the previous contributor to this monograph. WFR serves on advisory boards and educational faculties for Alexion Pharmaceuticals.
Associate Professor of Medicine
DD declares that he has no competing interests.
Department of Pathophysiology
University of Athens
PDZ declares that he has no competing interests.
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