Factor XII Activity

Casandra

Casandra Test Code LC06641Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 086322CPT Code 85280

Also known as: Hageman Factor, Surface Factor

Clinical Use

Order Test

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.

Test Details

Methodology

Immunoassay (Other)

Biomarkers

Factor XII

Protein

Factor XII Activity • Concentration / Level • Categorical (e.g., Positive / Negative / Indeterminate)

LOINC Codes

Order Codes

3232-6

Result Codes

3232-6

Result Turnaround Time

2-3 days

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.