Coagulation Factor XII Activity Assay, Plasma
Use
This test is important for diagnosing deficiency of coagulation factor XII and determining the cause of prolonged activated partial thromboplastin time (aPTT). Factor XII is involved in the intrinsic pathway and fibrinolytic systems. A deficiency is often discovered when aPTT is unexpectedly long, although it does not cause a known bleeding disorder. There has been a proposition but not proven association between severe deficiency and thrombosis risk.
Special Instructions
Coagulation testing is highly complex and often requires multiple assays and clinical correlation. Consider ordering a coagulation consultation to obtain comprehensive guidance. If priority processing is required, mark the request form, provide the reason, and request a call-back.
Limitations
Deficiencies in other contact activator proteins such as prekallikrein and high molecular weight kininogen can also lead to prolonged aPTT but do not cause clinical bleeding. Improper specimen collection or handling may cause diagnostic confusion.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 3232-6
- 3232-6
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of centrifuged vial. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or ideally, at or below -40 degrees C.
Patient Preparation
Patient must not be receiving Coumadin (warfarin) or heparin therapy.
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |