Frequency of severe ADAMTS13 deficiency (activity < 10%) among patients for whom PEX treatment was requested for an initial clinical diagnosis of TTP or HUS: the Oklahoma TTP-HUS Registry experience, 1995-2011
From November 13, 1995 through December 31, 2011, 301 (93%) of 333 consecutive patients enrolled in the Registry had ADAMTS13 activity measured in a sample obtained immediately before beginning the initial PEX by both FRETS and immunoblotting assays.3