Factor XII Activity

This test measures Factor XII, which initiates the intrinsic pathway of coagulation.

Diagnostic Value: Low Factor XII activity prolongs aPTT but typically does not cause bleeding; instead, some studies suggest it may increase thrombosis risk.

Clinical Significance: Helps explain isolated prolonged aPTT and distinguish it from true bleeding disorders.

Symptom Correlation: Usually asymptomatic, though linked to possible thrombotic tendency.

The Factor XII Activity test clarifies unexplained prolonged clotting results and assesses intrinsic pathway function.