Apixaban Anti Xa assay measures the blood concentration of oral anticoagulant apixaban and quantifies factor Xa inhibition of coagulation cascade with its anti-Xa effect. Patients treated for thromboembolism with apixaban should monitor its level with this assay. Tests assist healthcare professionals in adjusting proper apixaban dosage, tracking patients’ compliance with therapy, and minimising the risk of bleeding or thrombotic events.