Heparin Tubes are used in blood collection and anti-coagulation not only for routine clinical biochemistry tests and emergency biochemistry tests, but also for some test items in blood rheology. The interior of the tubes wall are coated with lithium heparin or sodium heparin to inhibit clotting. The anticoagulant heparin activates antithrombins, thus blocking the coagulation cascade and producing a whole blood / plasma sample instead of clotted blood and serum.