What is the primary application of Sodium Citrate in laboratory testing?

Sodium citrate is primarily used in laboratory testing for coagulation studies. It acts as an anticoagulant, which means it helps prevent blood from clotting during the testing process. When blood is drawn for coagulation tests, such as PT (prothrombin time) and aPTT (activated partial thromboplastin time), the use of sodium citrate ensures that the blood sample remains in a liquid state, allowing for accurate determination of various coagulation factors.

The mechanism by which sodium citrate works involves its ability to chelate calcium ions in the blood. Calcium is essential for the clotting process, and by binding to it, sodium citrate effectively inhibits the clotting cascade. This allows laboratory personnel to analyze the sample without interference from clot formation.

While alternatives are used for other purposes, such as preserving glycolytic activity (which relates to metabolic tests), sodium citrate specifically addresses the requirements of coagulation studies, making it an essential choice in this context. Other options like microbial testing and tissue typing utilize different preservatives or procedures that do not involve sodium citrate as their main application.