Which electrolytes are involved in blood coagulation?

• A. Ca, Mg
• B. Na, K
• C. Zn, Fe
• D. Cl, HCO3

Answer: (A)

Calcium ions are essential for blood coagulation. They act as a required cofactor for multiple coagulation factors and enable the assembly of enzyme complexes on platelet membranes, guiding the cascade from the initial activation steps to conversion of prothrombin to thrombin and fibrin formation. Without Ca2+, the coagulation process slows dramatically and tests of clotting time are prolonged.

Magnesium ions also contribute, serving as a cofactor for some enzymes and influencing platelet function, thereby supporting the calcium-dependent reactions in coagulation. Yet calcium is the primary driver of the cascade.

Sodium and potassium mainly regulate fluid balance and electrical activity in cells, not directly the clotting process. Zinc and iron are trace metals with roles in various enzymes but not as direct cofactors in the coagulation cascade. Chloride and bicarbonate are key for acid-base and electrolyte balance, not coagulation.