Volume 72 Number 3 May 2005	back to contents

1 Fellow in Hematology/Oncology and 2 Professor of Clinical Research in Hemophilia, Mount Sinai School of Medicine, New York, NY.

Address all correspondence to Louis M. Aledort, M.D., Department of Hematology, Box 1006 , Mount Sinai Medical Center, One East 100 th Street, New York, NY 10029.

Adapted from a Grand Rounds presentation to the Department of Medicine, Mount Sinai School of Medicine, New York, NY on November 11, 2003, and updated as of October 2004.

ABSTRACT

Several disease states manifest as thrombotic microangiopathies (TMA), most prominently thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). The recent discovery of the von Willebrand factor cleaving protease ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type 1 motif), found to be deficient in TTP, has helped separate these entities. In contrast, HUS is caused by direct endothelial damage by bacterial toxins, while in familial cases inappropriate complement activation through deficient factor H appears to be a major pathogenetic mechanism.

Although enormous progress has been made towards understanding these syndromes, the diagnostic tools and therapies used have hardly changed in the last 20 years, with the standard of care remaining plasma exchange in most cases. In this review, we will cover the multiple etiologic factors for TMAs, with the resultant differential diagnoses, as well as provide insight into the latest pathophysiologic findings and possible implications for treatment.

KEYWORDS

Thrombotic microangiopathy, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, von Willebrand factor, ADAMTS-13, plasma exchange.

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