In this case, with the pre-incubation aPTT mixing study result "corrected" and the post-incubation aPTT mixing study result "not corrected", a coagulation inhibitor should be suspected. Both anti-factor VIII and lupus anticoagulant have been known to be slow-acting and can exhibit this result pattern. If a factor deficiency was present, we should not see a post-incubation prolongation.

Hematology

What may cause the following mixing studies results?

Initial aPTT = 133 seconds

1:1 Mix aPTT pre-incubation = 33 seconds

1:1 Mix aPTT post-incubation = 124 seconds