Activated Partial Thromboplastin Time (aPTT)

Activated Partial Thromboplastin Time (aPTT) is a tested used to evaluate the intrinsic coagulation system. It aids the screen for congenital deficiencies of factors II, V, VIII, IX, X, XI and XII of the coagulation pathway. aPTT is also useful in the monitoring of heparin therapy. In addition, aPTT is used in the detection of Hemophilia A, Christmas disease, liver failure and Vitamin K deficiency. Furthermore, the test proveds screening for the presence of dysfibrinogenemia, disseminated intravascular coagulation, congenital deficiency of Fitzgerald factor and prekallikrein. aPTT is prolonged in the deficiency or inhition of any of the coagulation factors except factor VII. Coumadin therapy, heparin, aprotinin and lupus anticoagulants also have the same effect on aPTT. Prolonged aPTT is often evaluated with that of Prothrombin Time (PT) to assess coagulation system.


Coagulation Method

Coagulation Reaction Detection Method (Scattered Light Detection Method)

Irridates red light (660nm) onto a mixture of blood plasma and reagent and detects the change in turbidity (when fibrin clots are formed) as the change in scattered light. It measures the coagulation time.


Coagulation Point Detection Method (Percentage Detection Method)

Calculates the coagulation time as the time required to achieve the amount of scattered light that is set for the coagulation detection point, using the amount of scattered light that is present just after the start of detection as 0% and the amount of scattered light that is present at the completion of coagulation as 100%