Department of Haematology


  • Prolongation of the coagulation screen that can be significantly corrected by the addition of normal patient plasma may be the result of a specific factor deficiency.
  • Specific assays of each of the coagulation factors can be performed to determine the nature of the deficiency.
  • Samples that are under filled, overfilled or haemolysed give erroneous results and therefore will not be tested.
  • Tested at GRH or Oxford Haemophilia Centre.

Sample Requirements

2 x 3ml or 3.5ml Trisodium Citrate tubes x 2

3ml Trisodium citrate

Sample Suitability

Patients should not be on any form of anticoagulation at the time of testing. Sample stability at room temperature in 6 hours post venesection. All samples are centrifuged, aliquoted into LP4 tubes and frozen within this time period.

Turnaround Time

Urgent Factor VIII levels: within 4 hours

Routine: within 2 weeks

Please contact the laboratory in the first instance if urgent factor assays are required, especially outside of routine hours where the test will not be performed unless discussed directly with the laboratory. We aim to process urgent requests within 4 hours.

Reference Ranges

Test Range
Factor II 50 - 150%
Factor V 50 - 150%
Factor VII 50 - 129%
Factor VIII 50 - 150%
Factor IX 65 - 150%
Factor X 50 - 150%
Factor XI 65 - 150%
Factor XII 50 - 150%

Interfering substances

Anticoagulation therapy, haemolysed and lipaemic samples.

Add ons

Fresh samples are required.