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Test Directory -  Factor XI Assay


 Factor 11, F11

Clinical Indications

Unexplained post-traumatic bruising, menorrhagia, epistaxis and bleeding from mucous membranes. Prolonged bleeding following dental extractions or post-partum. Usually only found in Jews of Ashkenazi decent (from Eastern Europe)

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 xBlue 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.


  Anticoagulation, poor phlebotomy practice (activated clotting pathway)

Reference Range

50 150%



Version 1.0 / January 2013