Factor XII Activity (Pre-Kininogen) – Plasma

What Is Factor XII?

Factor XII, also called the 'contact factor,' plays a role in the intrinsic pathway of blood clotting and the activation of the kinin system. It helps convert prekallikrein into kallikrein, which then activates bradykinin—a substance that influences inflammation and vascular permeability. While its exact clinical significance in routine testing is limited, it can be evaluated in specialized contexts, such as hereditary disorders or research.

Why Might This Test Be Ordered?

A blood sample may be tested for Factor XII activity if you have a suspected inherited bleeding disorder (e.g., Factor XII deficiency), suspected hereditary angioedema, or if you’re undergoing evaluation for conditions involving abnormal blood clotting or inflammation. Some research studies may also request this test.

How Is This Test Performed?

A small blood sample is drawn from a vein, typically in the arm. The sample is processed to separate plasma, which is then analyzed using a specialized laboratory method to measure Factor XII activity levels.

What Do Results Mean?

Results are reported as a percentage or ratio relative to a reference range, but standard ranges vary by lab. Abnormally low levels may indicate inherited Factor XII deficiency, while elevated levels could suggest certain inflammatory conditions or laboratory artifacts. Consult your healthcare provider for interpretation.