Overview: Factor XII Functional TestIntroduction: The Factor XII Functional Test measures factor XII activity to diagnose clotting disorders, causing thrombosis or bleeding. Aligned with 2023 ASH guidelines, it uses a clotting assay for high specificity, aiding in coagulation screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in coagulation for patients with suspected clotting disorders.
Other Names: Factor XII Assay, Hageman Factor Test.
FDA Status: Laboratory-developed test (LDT), meeting coagulation standards for diagnostic accuracy.
Historical Milestone: Factor XII testing began in the 1950s with coagulation research. Functional assays emerged in the 1970s, and by the 2000s, standardized clotting assays improved accuracy.
Purpose: Diagnoses clotting disorders, guides anticoagulant therapy, and monitors factor XII activity in patients with thrombosis or bleeding.
Test Parameters: 1. Factor XII Activity
Pretest Condition: No fasting required. Collect plasma at any time. Report symptoms like thrombosis or bleeding, and list medications like anticoagulants.
Specimen: 2-4 mL plasma (NaCit). Centrifuge within 1 hour. Transport in a biohazard bag within 24 hours.
Sample Stability at Room Temperature: 24 hours
Sample Stability at Refrigeration: 48 hours
Sample Stability at Frozen: Not frozen
Medical History: Document thrombosis, bleeding, or history of clotting disorders. Include current medications, especially anticoagulants.
Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for anticoagulant therapy.
Procedural Considerations: Uses a clotting assay to measure factor XII activity. Results are available in 3-5 days, supporting clinical decisions.
Factors Affecting Result Accuracy: Anticoagulants or improper storage can affect results. Hemolysis may reduce accuracy.
Clinical Significance: Abnormal factor XII activity suggests clotting disorders, prompting anticoagulant therapy or further testing. Normal activity may require additional coagulation tests.
Specialist Consultation: Consult a hematologist for result interpretation.
Additional Supporting Tests: aPTT, factor XII mutation test, or D-dimer to confirm clotting disorders.
Test Limitations: Results may be affected by medications. Clinical correlation is required.
References: ASH Coagulation Guidelines, 2023; Journal of Thrombosis and Haemostasis, Weitz JI, 2022.
