Antithrombin III regulates blood clotting, acting as a natural anticoagulant protein. Measuring its concentration and activity is indicated to investigate abnormal blood coagulation to assess thrombosis risk. This test helps healthcare professionals diagnose and manage patients with recurrent thrombosis, thromboembolism, and hereditary or acquired clotting disorders. The test is an integral part of clotting assay for prophylactic interventions and therapeutic monitoring.