|Molecular mass||160 000 Da|
|Half life||60 - 80 hours|
|Plasma concentration||2 - 7 mg/l|
|Normal range||70 - 130 %|
During the contact activation phase of the intrinsic coagulation system factor XI is bound to negatively charged surfaces together with high molecular weight kininogen (HMWK). Factor XIIa activates bound factor XI. In the next step factor XIa activates factor IX. In plasma, factor XI is bound to HMWK.
Inherited factor XI deficiency is also know as hemophilia C or Rosenthal syndrome.. Although the condition can affect people of all heritages, it is most common in people of Ashkenazi Jewish descent. The genetic defect is inherited as an autosomal recessive trait. However, the associated bleeding tendency in these patients is low. Liver disease, consumption coagulopathy and DIC lead to an acquired factor XI deficiency. In cases of autoimmune diseases, e.g. Lupus erythematosus, inhibitors against factor XI may be observed. Inhibitors may also be observed after substitution therapy. Recent findings suggest a correlation between increased levels of factor IX and VTE.
- Suspected inherited factor XI deficiency
- Suspected factor XI inhibitors
- Differential diagnosis in patients with Lupus anticoagulants
- Suspected disorders of the kallikrein-kinin system
- Diagnosis of thrombophilia
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