What is sodium citrate used for in laboratory tests?

Sodium citrate is primarily utilized as an anticoagulant in coagulation tests. Its role is to bind calcium ions in the blood, which are essential for the clotting process. By chelating calcium, sodium citrate prevents the blood from clotting, allowing for accurate measurements of various coagulation parameters such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). This function is vital for diagnosing bleeding disorders and monitoring patients on anticoagulant therapy.

In contrast, options suggesting that sodium citrate is a preservative, a coagulant for serum samples, or a stabilizing agent for glucose tests do not accurately reflect its clinical application. Preservatives are typically different substances designed to maintain the integrity of samples over time, while coagulants would promote clotting rather than prevent it. Additionally, glucose tests utilize sodium fluoride or other agents for stabilization, not sodium citrate. Thus, sodium citrate’s specific role as an anticoagulant makes it essential for the accuracy of coagulation tests.