How do you approach a patient with chronic low ADAMTS13 activity and low level of inhibitor without signs of thrombocytopenia or hemolysis?  

I'm assuming there is a history of overt TTP that led to the ADAMTS13 level being measured.In patients with a history of TTP, I monitor the ADAMTS13 level every 1-6 months (more often if the level is lower or dropping) and administer a single dose of rituximab if it drops below 20%. In my experience...