Hemolytic anemia characterized by evidence of intravascular hemolysis such as hemoglobinuria and elevation of plasma lactate dehydrogenase.
Diagnosis can be made by flow cytometry of granulocytes and RBCs, 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).
May arise in patients with or recovering from aplastic anemia, and it may manifest with cytopenias that are the result of marrow hypoproduction, which may respond to treatment for aplastic anemia.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder of the blood characterized by intravascular hemolysis 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 topic. 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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