Coagulation factor XII

General Information

Coagulation factor XII or Hagemann's factor is a glycoprotein synthesized in the liver, which together with prekallikrein and high molecular weight kininogen forms a contact-activation system. These factors are essential for in vitro thrombus formation as determined by the activated partial thromboplastin time (APTT). In a test tube (in-vitro), factor XII is activated upon contact with negatively charged surfaces.

In case of deficiency of this factor, hemorrhagic manifestations are not observed, because physiological coagulation occurs in an alternative way, bypassing the contact-activation system.

FXII deficiency is a genetic disorder with autosomal recessive inheritance. Heterozygous (simultaneous presence of a healthy and mutated gene) condition is more common and occurs in 1,5-3% of the population. Factor FXII deficiency is the most common cause of APTT prolongation in patients with no history of hemorrhagic syndrome and a negative lupus anticoagulant.

In homozygous (both mutated genes) individuals, factor xii activity is <1% and may be associated with APTT prolongation >100 seconds.

Factor XII changes (both increase and decrease) may be detected in specific clinical conditions, such as: septicemia, coronary artery diseases, pharmacological thrombolysis, inflammatory bowel diseases, pregnancy, lactic acidosis, dialysis, angioedema.

Determination of factor XII is recommended to determine the causes of APTT prolongation even when it is not associated with bleeding.

Preparation of the patient: The study is conducted on an empty stomach

Material for examination: Venous blood

Reference norms

50-150%

1-15 weeks of pregnancy: 50-150 %

16-40 weeks of pregnancy: 50-170%