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).