Definition

Noun: * Coagulation Factor XII: A specific protein in the blood plasma that is part of the intrinsic pathway of the coagulation cascade. When it comes into contact with negatively charged surfaces (like collagen exposed by an injury or glass in a test tube), it is activated and initiates a series of reactions that lead to blood clot formation. Its deficiency is notable for prolonging laboratory clotting tests but typically does not cause abnormal bleeding.

Usage

• The term is used primarily in medical, biological, and clinical laboratory contexts to discuss blood coagulation.
• It is often discussed in relation to its function, its role in laboratory diagnostics, or its deficiency.

Examples

• "The activated partial thromboplastin time (aPTT) test is sensitive to deficiencies in Hageman factor and other intrinsic pathway factors."
• "Despite a documented Hageman factor deficiency, the patient did not exhibit a clinical bleeding tendency."
• "Research focuses on the role of Hageman factor in initiating both coagulation and inflammatory responses."

Advanced Usage

• Hageman factor deficiency: A congenital condition, also known as Factor XII deficiency. It is usually asymptomatic (does not cause bleeding) but is identified through prolonged clotting times in laboratory tests like the aPTT.
• Activated Hageman factor (Factor XIIa): The enzymatically active form of the protein that triggers the next steps in the coagulation cascade.

Variants and Related Words

• Factor XII: The standard international nomenclature and a direct synonym.
• Contact factor: A broader term that can refer to Hageman factor (Factor XII) and other factors initiated by surface contact.
• Coagulation factor: The general category of proteins to which Hageman factor belongs.
• F12 gene: The gene that provides instructions for making coagulation Factor XII.

Synonyms

• Factor XII
• Contact factor (in specific contexts)

Notes on Meaning

While "Hageman factor" strictly refers to the protein itself (Factor XII), it is intrinsically linked to the condition of its deficiency. The key distinction is that the word names the protein, but its usage frequently involves discussion of the physiological state when that protein is absent or dysfunctional.

Noun

1. coagulation factor whose deficiency results in prolongation of clotting time of venous blood