If a patient's PT is normal and their APTT is prolonged, and corrects with a 1:1 mix with normal plasma, this could be due to:

Question

Quizplus · Accepted Answer

A prolonged APTT with correction by a 1:1 mix suggests a factor deficiency. The most likely factor to be deficient is factor VIII, IX or XI. Factor V and II deficiencies are rare and typically do not cause a prolonged APTT. Factor VII deficiency can cause a prolonged PT but not APTT. Therefore, the best choice is C, which is Factor IX deficiency.

If a Patient's PT Is Normal and Their APTT Is