Algorithm for the management of patients with TTP-HUS.

Solid arrows represent an ideal course; broken arrows represent common variations. The decision to initiate plasma exchange, often the most difficult step, is addressed in Tables 1 to 3. Once treatment is initiated, physicians must remain alert for alternative diagnoses. A “poor response” is not easily defined. It may indicate persistent, severe thrombocytopenia and hemolysis after several days of plasma exchange, or it may indicate recurrent, acute thrombocytopenia and hemolysis after an initial good response, or the appearance of new neurologic abnormalities, while the patient is continued on once daily plasma exchange. Consolidation treatment is empirical and is based only on observations that exacerbations of TTP-HUS are common when plasma exchange is stopped. Other considerations, such as complications with venous access, may override a decision to extend treatment. In many patients, repeated reinitiation of daily plasma exchange is required before durable complete remission is established. No maintenance treatment or specific diagnostic test appears to prevent or predict a relapse. The definitions of exacerbation and relapse, as occurring within or beyond 30 days of remission, are arbitrary.