Guidelines on the diagnosis and management of the thrombotic microangiopathic haemolytic anaemias. Allford SL, Hunt BJ, Rose P, Machin SJ; Haemostasis and Thrombosis Task Force, British Committee for Standards in Haematology. British Journal of Haematology 2003;120(4):556-573.

ABSTRACT:

Thrombotic thrombocytopenic purpura (TTP) is rare but its prompt recognition and treatment is vital. TTP is a clinical diagnosis, and a number of different clinical variants of TTP have been documented. This paper describes the various subtypes in terms of pathogenesis, laboratory features, and management guidelines. Of particular note is acute TTP. Although E. coli O157:H7 is more closely linked with hemolytic uremic syndrome (HUS), there have been cases with typical TTP features. The mainstay of treatment in acute TTP is daily plasma exchange (PE). Mortality rates have fallen from 90% or more to 10-30% since the institution of PE. PE is superior to plasma infusion with improved response rates and decreased mortality. PE should be instituted within 24 hours of presentation as delay in treatment may increase treatment failure. Reduced level of consciousness has been identified as a poor prognostic factor with an overall survival of 54%. The duration of treatment to achieve remission is highly variable and the optimal regimen has not been determined. It is empirically recommended that daily exchanges should continue for a minimum of two days after complete remission is obtained. As the premature omission of a single PE may be associated with exacerbation, patients should be treated in centers able to provide daily service. Steroids have been widely used in the treatment of TTP although there is scanty evidence of its efficacy. Patients with TTP lacking central nervous system abnormalities, however, have been shown to respond to steroid treatment alone. Steroids have also been combined with PE in initial treatment of TTP but no study has addressed whether combination therapy is superior to PE alone. The use of anti-platelet agents in TTP remains controversial. Other treatment recommendations include: red cell transfusion according to clinical need, folate supplementation in all patients, platelet transfusions are contraindicated in TTP unless there is life-threatening hemorrhage, and hepatitis B vaccination is recommended in all patients. This paper also outlines the management of refractory TTP. Diarrhea-associated HUS, on the other hand, is not an indication for PE, fresh frozen plasma infusion, or other adjunctive treatment. Careful rehydration, hypertension control, and renal dialysis as required are recommended. Blood transfusions should be given as needed but platelet transfusions avoided.