hematology and oncology
Elevated Factor VIII, IX, and XI Levels
Diagnosis of Elevated Factor VIII, IX, and XI Levels
Measurement of factor VIII, IX, or XI Levels of VIII, IX, and XI antigen and activity can be directly measured. activity when the patient is not taking anticoagulants and is unaffected by an infection or inflammatory conditions ( Diagnosis reference ). Factor VIIIlevels are also increased by pregnancy,estrogen-containing hormonal therapy, cancer, liver disease, kidney disease, hyperthyroidism, intravascular hemolysis, and exercise. Measurement offactor VIIIactivity in a patient taking anticoagulants will result in falsely reducedfactor VIIIactivity.Factor VIIIantigen is not affected by anticoagulation. In contrast,Factor VIIIantigen and activity levels increase with systemic inflammation and many other conditions (see above) so measurement offactor VIIIis ideally done in the absence of these disorders. Factor IXantigen can be reduced by vitamin K antagonists but not direct oral anticoagulants. Factor XI antigen is not affected by anticoagulation.Factor IXand XI activity levels are reduced by anticoagulation. 1.O'Donnell J, Tuddenham EG, Manning R, Kemball-Cook G, Johnson D, Laffan M. High prevalence of elevatedfactor VIIIlevels in patients referred for thrombophilia screening: role of increased synthesis and relationship to the acute phase reaction.Thromb Haemost1997; 77(5):825-828. PMID: 9184386 