PT tube is used for blood coagulation test and applicable to fibrinolytic system(PT,TT, APTT and fibrinogen, etc. ). The mixing ratio is 1 part citrate to 9 parts blood. Accurate ratio can guarantee effectivity of the testing result and avoid misdiagnosis. As the sodium citrate has little toxicity, it is also used for blood storage. Do draw sufficient blood volume to ensure accurate testing result.