Interpretation for Mixing Study/ Incubated APTT
1. If the APTT Screen is prolonged with a normal APTT Immediate Mix and APTT Incubated mix, this indicates a factor deficiency in the intrinsic or final common pathway. If the PT is normal, this suggests an intrinsic pathway deficiency (VIII, IX, XI, XII, PK, HMWK). If the PT is prolonged, this suggests a common pathway deficiency (fibrinogen, II, V, X).
2. If the APTT Screen is prolonged, with a normal APTT Immediate Mix, but an abnormal APTT Incubated Mix, this indicates the presence of a delayed inhibitor such as specific factor inhibitors, most commonly factor VIII inhibitor, and small numbers of lupus anticoagulant.
3. If the APTT Screen is prolonged, with an abnormal APTT Immediate Mix and abnormal APTT Incubated Mix, this favors a non-specific inhibitor such as a lupus anticoagulant, and anticoagulants such as heparin, fondaparinux, dabigatran or other direct thrombin inhibitors.
1. If the APTT Screen is prolonged with a normal APTT Immediate Mix and APTT Incubated mix, this indicates a factor deficiency in the intrinsic or final common pathway. If the PT is normal, this suggests an intrinsic pathway deficiency (VIII, IX, XI, XII, PK, HMWK). If the PT is prolonged, this suggests a common pathway deficiency (fibrinogen, II, V, X).
2. If the APTT Screen is prolonged, with a normal APTT Immediate Mix, but an abnormal APTT Incubated Mix, this indicates the presence of a delayed inhibitor such as specific factor inhibitors, most commonly factor VIII inhibitor, and small numbers of lupus anticoagulant.
3. If the APTT Screen is prolonged, with an abnormal APTT Immediate Mix and abnormal APTT Incubated Mix, this favors a non-specific inhibitor such as a lupus anticoagulant, and anticoagulants such as heparin, fondaparinux, dabigatran or other direct thrombin inhibitors.
Diagnosis: Henoch–Schönlein purpura with anti-phospholipid antibody.