- See: clotting cascade

- Prothrombin Time (PT) 11.5-13.5 sec
- PT is used to evaluate extrinsic clotting mechanism: I, II, V, VII, X;
- Prolonged:
- coumadin;
- vit K deficiency;
- fat malabsorption
- liver dz

- Partial Thromboplastin TIME (PTT) 27-38 sec;
- tests intrinsic & common coag pathways (XII, XI, IX, VIII, X, V, II);
- prolonged: heparin and any defect in the intrinsic clotting mechanism hemophilia A & B and lupus anticoagulant

In vivo study of bleeding time and arterial hemorrhage in hypothermic versus normothermic animals.

Effect of laboratory variation in the prothrombin-time ratio on the results of oral anticoagulant therapy.