Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: pathophysiology and management.

Pathogenic mechanisms of renal injury by thrombotic microangiopathies present a challenge to the multidisciplinary team caring for a patient with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS). First recognized 77 years ago as a rare disorder characterized by reversible platelet aggregation in the microcirculation causing ischemia in various organs, the prognosis was always fatal. In the past 20 years, due to effective treatment with plasma exchange therapy, there has been a decline in the mortality rate to 10-20%. The classic pentad of symptoms of TPP-HUS include thrombocytopenia, microangiopathic hemolytic anemia, neurologic abnormalities, fever, and renal impairment. Frequency of TTP-HUS appears to be increasing. Due to the urgent need for a diagnosis, sufficient diagnostic criteria for TTP-HUS are currently thrombocytopenia and microangiopathic hemolytic anemia in the absence of another apparent cause. It is imperative to have a solid understanding of the pathophysiology and current standards of practice of TTP-HUS in order to facilitate positive patient outcomes in this unique group of patients.