Coagulation screen

 

Alternative names, keywords

APTT ratio, activated partial thromboplastin time ratio, INR, international normalized ratio, clotting screen, fibrinogen (Clauss).

Samples required

Trisodium citrate blood (blue cap, 3.5 mL tube) taken with minimal stasis, filled to the line. Smaller tubes are available for paediatric samples.

Samples must be analysed or processed in the laboratory within 4 hours of venepuncture.

Test indications

 

Reference range

INR

0.8 - 1.2

APTT

24.8 - 37.4 s

APTT ratio

0.87 - 1.15

Prothrombin time

11 - 17 s

Fibrinogen (Clauss)

1.8 - 4.5 g/L

Source: locally determined.

Turnaround time

1 working day (2 hours if identified as urgent).

Enquiries

Haematology (Coagulation)