Prothrombin Time (PT)
The prothrombin time is sensitive to, and thus prolonged in, patients with deficiencies of factors VII, X, V, II and fibrinogen. It is particularly useful in monitoring anticoagulation in patients on warfarin.
Interpretation of a prolonged Prothrombin Time (PT)
[click here to download a pdf version of this flow chart]
Reference:
Kitchen S, Makris M. Laboratory Tests in Haemostasis. in Makris M, Lillcrap D, O'Shaughnessy, D. (eds). Practical Haemostasis and Thrombosis (2005). Blackwell Publishing.
Activated Partial Thromboplastin Time (APTT)
This test is abnormal in patients with deficiencies of factors XII, XI, X, IX, VIII, V, II and fibrinogen, those on heparin therapy or who have the lupus anticoagulant.
Interpretation of a prolonged Activated Partial Thromboplastin Time (APTT)
[click here to download a pdf version of this flow chart]
Reference:
Kitchen S, Makris M. Laboratory Tests in Haemostasis. in Makris M, Lillcrap D, O'Shaughnessy, D. (eds). Practical Haemostasis and Thrombosis (2005). Blackwell Publishing.
The Thrombin Time (TT)
It is sensitive to, and thus prolonged in, hypo- and dysfibrinogenemia, heparin therapy (or heparin contamination of the sample), or in the presence of fibrin(ogen) degradation products and factors that influence the fibrin polymerization (eg the presence of a paraprotein in myeloma).
Interpretation of a prolonged Thrombin Time (TT)
[click here to download a pdf version of this flow chart]
Reference:
Kitchen S, Makris M. Laboratory Tests in Haemostasis. in Makris M, Lillcrap D, O'Shaughnessy, D. (eds). Practical Haemostasis and Thrombosis (2005). Blackwell Publishing.