Table 2

Test result
Cause

PT prolonged, aPTT normal
Factor VII deficiency

Mild vitamin K deficiency

Mild liver insufficiency

Low doses of vitamin K antagonists
PT normal, aPTT prolonged
Factor VIII, IX, or XI deficiency

Use of unfractionated heparin

Inhibiting antibody and/or anti-phospholipid antibody

Factor XII or prekallikrein deficiency (no relevance for in vivo coagulation)
Both PT and aPTT prolonged
Factor X, V, II or fibrinogen deficiency

Severe vitamin K deficiency

Use of vitamin K antagonists

Global clotting factor deficiency

     Synthesis: liver failure

     Loss: massive bleeding

     Consumption: DIC

aPTT, activated partial thromboplastin time; PT, prothrombin time.

Levi and Opal Critical Care 2006 10:222   doi:10.1186/cc4975