PT and/or aPTT may be prolonged for several reasons.
Table 3. Conditions Resulting in Prolonged PT or aPTT. | Prolonged PT | Prolonged aPTT |
| Warfarin therapy | Presence of heparin |
| Liver disease | Liver disease and other liver conditions |
| Disseminated intravascular coagulation (DIC) | DIC |
| Vitamin K deficiency | Vitamin K deficiency |
| Liver conditions such as cirrhosis or hepatitis | Hemophilias |
| Inadequate levels of factors I, II, V, VII, and/or X | von Willebrand disease (vWD) |
| Lupus anticoagulant |
| Inadequate levels of factors I, II, V, VIII, IX, X, XI, and/or XII |
