The typical reference range is between 30 seconds and 50 s (depending on laboratory). Shortening of the<unk>  is considered to have little clinical relevance, but some research indicates that it might increase risk of thromboembolism. Normal<unk> <unk> s require the presence of the following coagulation factors: I, II, V, VIII, IX, X, XI and XII. Notably, deficiencies in factors VII or XIII will not be detected with the<unk>  test. Prolonged aPTT may indicate: * use of heparin (or contamination of the sample) * antiphospholipid antibody (especially lupus anticoagulant, which paradoxically increases propensity to thrombosis) * coagulation factor deficiency (e.g., hemophilia) * sepsis — coagulation factor consumption * presence of antibodies against coagulation factors (factor inhibitors) To distinguish the above causes, mixing tests are performed, in which the patient's plasma is mixed (initially at a 50:50 dilution) with normal plasma. If the abnormality does not disappear, the sample is said to contain an "inhibitor" (either heparin, antiphospholipid antibodies or coagulation factor specific inhibitors), while if it does disappear a factor deficiency is more likely. Deficiencies of factors VIII, IX, XI and XII and rarely von Willebrand factor (if causing a low factor VIII level) may lead to a prolonged aPTT correcting on mixing studies. The aPTT is usually normal in pregnancy but tends to slightly decrease in late pregnancy.
Partial thromboplastin time
Activated clotting time
Thrombin time
Prothrombin time
Kaolin clotting time
Ecarin clotting time
Clotting time
Reptilase time