PTD - 19

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Test Directory -  Factor XII Assay


  F12, Factor 12

Clinical Indications

No abnormal bleeding or bruising reported. Diagnosis is usually coincidental.

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 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.


  Anticoagulation, poor phlebotomy practice (activated clotting pathway)

Reference Range

50 150 %



Version 1.0 / January 2013