Role of Calcium in the Coagulation Cascade

Introduction to Calcium's Role

Calcium acts as an essential cofactor in the activation of multiple coagulation factors, including factors II, VII, IX, and X, as well as proteins C and S, and is necessary for platelet adhesion at sites of vessel injury 1, 2

Calcium ions are required for the formation and stabilization of fibrin polymerization sites 1
Calcium functions as a cofactor in the activation of vitamin K-dependent coagulation factors, including Factor II (prothrombin), Factor VII, Factor IX, Factor X, Protein C, and Protein S 1
Calcium is necessary for platelet adhesion at the site of vessel injury 1
Calcium enables binding of coagulation factors to membranes of cells and extracellular vesicles, which is a prerequisite for thrombin formation 3

Hypocalcemia (low calcium levels) negatively impacts both coagulation and platelet function 1
Ionized calcium levels below 0.9 mmol/L can lead to coagulation abnormalities 1
Severe hypocalcemia (ionized Ca²⁺ levels below 0.8 mmol/L) is associated with cardiac dysrhythmias 1
Hypocalcemia within the first 24 hours of critical bleeding can predict mortality and the need for multiple transfusions with greater accuracy than other coagulation parameters 1
Anticoagulants like citrate work by chelating calcium ions, thereby preventing coagulation 3

Calcium levels should be monitored and maintained within the normal range (1.1-1.3 mmol/L) following major trauma and during massive transfusion 1
Calcium chloride is the preferred agent to correct hypocalcemia in clinical settings 1