Specimen Collection

Collection of samples for Factor VIII

• A trough level should be collected just before giving a FactorVIII dose.
• A peak level should be taken 30 minutes after the dose.

Requests for Chromogenic FVIII must be referred through a Haematologist or Haemophilia Centre.

Citrated platelet poor plasma. Minimum volume 0.5 mL.

2.7 mL Adult Citrate Blood

or

1.8 mL 2xCitrate Blood

If the specimen is collected from outside Auckland Hospital: send 2x 1.5 ml plasma aliquot, frozen.

• Filtered plasma is unsuitable and may lead to erroneously low results.

Reference Intervals

Normal Reference Intervals:

Factors VIII and IX

55 - 150%

Factors	Uncertainty of measurement
VIII , IX, XI , XII	18%

• Paediatric reference intervals are age stratified and given on the result report

Turnaround Time: Within 2 weeks

Unless URGENT

Diagnostic Use and Interpretation

Factor assays are generally used to identify the cause of bleeding disorders. However, factors II, VII and VIII are included in the investigation of thrombosis.

The Chromogenic FVIII is used in suspected mild haemophilia A and not usually required for management. Requests for Chromogenic FVIII must be referred through a Haematologist or Haemophilia Centre.

See Bleeding History

Limitations of procedure:

Factor assays may be affected by sample activation or the presence of inhibitors.

Interpretation:

Coagulation factors may be reduced due to defective production (congenital or acquired defects), consumption (DIC), dilution (massive transfusion), destruction (specific inhibitors), and in the case of factors II, VII, IX, or X, vitamin K deficiency/warfarin ingestion.

Contact Information

For further information contact the Haematology laboratory (Ext 22067) or:

Dr Nicola Eaddy	Ext 22005
Dr Peter Bradbeer	Ext 22062
Dr Anna Ruskova	Ext 22137
Dr Nikhil Rabade	Ext 22071

Last updated at 13:09:28 11/09/2024