PTD - 16

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Test Directory -  Factor VIII Assay


Haemophilia screen, Haemophilia A, Factor 8, F8

Clinical Indications

Excessive bleeding, especially haemarthrosis. Severe unexplained or excessive bruising. The deficiency is very rare in female patients.

Request Form

Combined Pathology Blood form (Yellow/Black or Blue for GP's)


Available routinely, samples analysed within  two weeks of receipt, unless required urgently Please discuss with Consultant Haematologist before requesting.

Specific Criteria

Patient should be bled with minimal stasis, and samples received in lab within 4 hours of collection. All requests are reviewed by Consultant Haematologist before testing.

Turnaround Time

Analysed within two weeks of receipt. Contact laboratory if urgent (Ext:1241)


Citrated Blood




3 x  Blue capped vacutainer tubes

Lab. Handling

Samples double spun and frozen.

Causes for Rejection

Mislabelled / unlabelled samples. Underfilled, clotted or haemolysed samples. Patient on anticoagulant therapy. Failure to meet specified criteria.  Post DDAVP treatment (except when monitoring)


  Anticoagulation, poor phlebotomy practice (activated clotting pathway)

Reference Range

50 150%



Version 1.0 / January 2013