Measuring ADAMTS-13 activity levels may not guarantee initial diagnosis and therapeutic decisions, but it is important for the prognosis. An ADAMTS-13 activity level < 5% - 10% seems to have increased specificity for TTP, but it does not identify all patients at risk for relapsing. ADAMTS-13 activity levels of > 10% makes the diagnosis of TTP unlikely in patients presenting with acute thrombocytopenia (10, 19, 20). Sometimes transfusion of fresh frozen plasma may increase ADAMTS-13 activity levels which may alter diagnosis.

Therapeutic plasma exchange is the main therapy for patients with TTP (21). Plasma exchange delivers elevated ADAMTS-13 dose without circulatory overload and removes antibodies to ADAMTS-13, recovering ADAMTS-13 activity. The treatment approach consists of a 1 to 1.5 plasma volume exchange with plasma daily until clinical symptoms have resolved and the platelet count has reached a normal level (22). Our patient’s condition resolved after undergoing 7 sessions of plasmapheresis. LDH levels should also be monitored since it reflects ongoing tissue ischemia as well as haemolysis. Treatment with immunosuppressive agents is reserved for patients suspected of having ADAMTS-13 autoimmune deficiency. Glucocorticoids are the immunosuppressive agents initially administered. Other agents such as rituximab and cyclosporine are used for more critically ill patients and patients with recurrent disease (23, 24).