Most anticoagulants work by:

Most anticoagulants work by:

• A. Inhibiting Thrombin Directly
• B. Activating Platelets
• C. Destroying Red Blood Cells
• D. Binding to Calcium

Answer: (D)

Calcium is a required cofactor at several steps of the coagulation cascade, so removing it or blocking its action can prevent clotting. That’s why calcium-binding agents like citrate are used in the lab to keep drawn blood from clotting. But most anticoagulants used clinically to prevent thrombosis don’t work by binding calcium. They interfere with the cascade by more direct mechanisms: some inhibit thrombin or factor Xa, others reduce the production of vitamin K–dependent clotting factors, and some directly inhibit thrombin. In short, the common way anticoagulants prevent clotting is by targeting specific steps or factors in the coagulation process, not by sequestering calcium in the body.

Calcium is a required cofactor at several steps of the coagulation cascade, so removing it or blocking its action can prevent clotting. That’s why calcium-binding agents like citrate are used in the lab to keep drawn blood from clotting. But most anticoagulants used clinically to prevent thrombosis don’t work by binding calcium. They interfere with the cascade by more direct mechanisms: some inhibit thrombin or factor Xa, others reduce the production of vitamin K–dependent clotting factors, and some directly inhibit thrombin. In short, the common way anticoagulants prevent clotting is by targeting specific steps or factors in the coagulation process, not by sequestering calcium in the body.