APTT ratio - therapeutic heparin ratio


Alternative names, keywords


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

2.0 – 2.5

Source: locally determined.

Turnaround time

1 working day


Haematology (Coagulation)