Screening Tests: Summary

The following table provides a summary of the results obtained using the PT, APTT, Fibrinogen and Thrombin Time in various disorders.

 

Platelet Count

PT

APTT

TT

Fibrinogen

Possibilities

A.

Normal

Normal

Normal

Normal

Normal

Normal profile
Factor XIII deficiency
Mild VWD
Qualitative platelet disorder
Connective tissue problem e.g. Ehlers Danlos
Mild coagulation factor deficiency

B.

Normal

↑

Normal

Normal

Normal

FVII deficiency

C.

Normal

Normal

↑

Normal

Normal

FVIII, FIX, FXI or FXII deficiency
Lupus anticoagulant [Antiphospholipid antibody]

D.

Normal

↑

↑

Normal

Normal

Common pathway deficiency i.e. FII, FV or FX deficiency
Multiple clotting factor deficiencies e.g. combined V and VIII deficiency
Warfarin or vitamin K antagonist
Vitamin K deficiency
Occasionally a very strong Lupus anticoagulant [Antiphospholipid antibody] can cause these findings but it is unusual to see a prolongation of the PT with a LA due to the high concentration of PL i used an the PT test.

E.

Normal

↑

↑

↑

Normal or ↓

DIC
Massive transfusion
TTP
Possibly liver disease although the platelet count is usually reduced

F.

↓

Normal

Normal

Normal

Normal

Primary platelet problem e.g. ITP. The Mean Platelet Volume [MPV] can be helpful in establishing the causes of the thrombocytopaenia.
A raised MPV is often associated with increased peripheral destruction e.g. ITP whereas a reduced MPV is often seen in bone marrow failures.
Changes in the MPV are also seen in patients with various inherited plated disorders.

G.

↓

↑

↑

↑

↓

DIC
Dilutional coagulopathy
Liver disease

 

Data Interpretation

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