A Patient Is Admitted Through the Hospital Emergency Department with Thrombosis

A patient is admitted through the hospital emergency department with thrombosis, and heparin is initially begun. Her baseline PTT, before heparin therapy, is prolonged at 68 seconds. Further laboratory studies determine that she has the lupus anticoagulant. What test should be used to monitor her heparin therapy?

A) PTT
B) PTT after first adding antithrombin to her plasma
C) Chromogenic anti-Xa assay
D) TT after first making a 1:10 dilution of the patient plasma