How does citrate keep blood from clotting?

How does citrate keep blood from clotting?

• A. Citrate dissolves fibrin
• B. Citrate is a pH buffer that prevents clotting
• C. Sodium citrate ions block the calcium in the blood from initiating clotting factors
• D. Citrate neutralizes thrombin

Answer: (C)

Calcium ions are essential cofactors for many steps in the blood clotting cascade, helping activate clotting factors and convert fibrinogen to fibrin. Sodium citrate works by binding calcium ions, reducing the amount of free ionized calcium available. With calcium effectively sequestered, the coagulation cascade can’t proceed, so clotting is prevented in the blood sample. This effect is reversible if calcium is added back. The other ideas aren’t correct because citrate doesn’t dissolve fibrin, isn’t acting primarily as a pH buffer, and doesn’t neutralize thrombin; it simply removes the calcium needed to drive the clotting process.

Calcium ions are essential cofactors for many steps in the blood clotting cascade, helping activate clotting factors and convert fibrinogen to fibrin. Sodium citrate works by binding calcium ions, reducing the amount of free ionized calcium available. With calcium effectively sequestered, the coagulation cascade can’t proceed, so clotting is prevented in the blood sample. This effect is reversible if calcium is added back. The other ideas aren’t correct because citrate doesn’t dissolve fibrin, isn’t acting primarily as a pH buffer, and doesn’t neutralize thrombin; it simply removes the calcium needed to drive the clotting process.