The Prolonged PT

Evaluate a prolonged PT with a PT mixing study. The PT mixing study will clarify whether the prolonged PT is due to a factor deficiency or inhibitor. Rarely, an isolated prolonged PT is due to congenital factor VII deficiency. More commonly, an isolated prolonged PT is due to acquired factor VII deficiency, which can occur with vitamin K deficiency, warfarin use, liver disease, or disseminated intravascular coagulation.