Heparin lithium is a commonly used blood anticoagulant, widely used in clinical testing. Its mechanism of action is that heparin can bind to antithrombin III, significantly accelerating its inactivation of serine proteases such as thrombin, thereby blocking the coagulation cascade reaction and effectively preventing blood clotting.

It is usually used in conjunction with inert separation gel in vacuum blood collection tubes. After centrifugation, the separation gel forms a physical barrier between plasma and blood cells, achieving rapid separation. This sample can be used for direct instrument detection and remains stable for 48 hours under refrigeration.