Factor XII Activity
Also known as: Hageman Factor, Surface Factor
Use
Evaluate a prolonged aPTT and detect specific coagulation factor XII activity6,7
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions. The patient should ideally not be on anticoagulant therapy; avoid warfarin therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days beforehand.
Limitations
Direct Xa or thrombin inhibitor therapy may cause factitiously low results. Factor XII can be affected by conditions such as septicemia, coronary artery disease, thrombolysis, inflammatory bowel disease, pregnancy, lactic acidosis, hemodialysis, and angioedema. Decreased levels can be seen in liver and renal disease. Although congenital factor XII deficiency may increase venous thrombosis, recent findings suggest no hypercoagulability in patients homozygously deficient for factor XII.
Methodology
Immunoassay (Other)
Biomarkers
LOINC Codes
- 3232-6
- 3232-6
Result Turnaround Time
2-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
Not provided
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio. Mix immediately by gentle inversion at least six times. A discard tube is required if using a winged collection system.
Patient Preparation
Avoid anticoagulant therapy; avoid warfarin for two weeks and heparin, direct Xa, and thrombin inhibitors for three days prior. Do not draw from an arm with a heparin lock or catheter.
Storage Instructions
Freeze.
Causes for Rejection
Severe hemolysis; improper labeling; clotted specimen; diluted with IV fluids; thawed in transit; improper type; out of stability
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 28 days |