Mediterr J Rheumatol 2015; 26(2): 12-17
Thrombotic thrombopenic purpura-an unusual manifestation of rheumatic diseases
Authors Information
Department of Rheumatology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
Thrombotic thrombopenic purpura (TTP) belongs to a group of syndromes, known as thrombotic microangiopathy (TMA). Thrombotic microangiopathy is caused by thrombosis and injury of endothelial cells in small vessels (microangiopathy) that results in microangiopathic haemolytic anaemia (MAHA), consumptive thrombocytopenia, and organ injury. Thrombotic thrombopenic purpura is caused by deficiency of ADAMTS13 (A Disintegrin And Metalloproteinase with Thrombospondin Type 1 motif, member 13) that cleaves von Willebrand factor polymers. ADAMTS13 deficiency may be hereditary or acquired. Hereditary ADAMTS13 deficiency is caused by mutation of the relevant gene. Acquired ADAMTS13 deficiency is caused by anti-ADAMTS13 inhibitory autoantibodies. The latter is idiopathic or secondary to systemic lupus erythematosus.  Microangiopathic haemolytic anaemia is haemolytic anaemia (elevated serum LDH and indirect bilirubin) which is not autoimmune (direct Coombs test negative) and intravascular (schistocytes in peripheral blood smear, low-to-absent haptoglobin). Thrombocytopenia in TTP is severe with very low <30,000/uL) platelet count. The organ most frequently affected is central nervous system whereas renal injury is not frequent. The mainstay of treatment is plasma exchange which is very effective but must start as soon as possible for optimal effectiveness. Additional immunosuppressants to prevent relapses include steroids, rituximab, cyclophosphamide and others.