What is factor X deficiency?

Updated: Oct 28, 2019
  • Author: Muhammad A Mir, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

Factor X deficiency is a coagulation disorder usually inherited as an autosomal recessive trait, though it can be acquired. This deficiency is characterized by defective activity in both the intrinsic and extrinsic pathways, impaired thromboplastin time, and impaired prothrombin consumption. Factor X circulates as a serine protease that is activated at the point of convergence of the intrinsic and extrinsic coagulation pathways. Activated factor Xa is involved in macromolecular complex formation with its cofactor factor Va, a phospholipid surface, and calcium to convert prothrombin into thrombin. [99] Both PT and aPTT are prolonged.

Factor X deficiency may be acquired in patients with light chain–related amyloidosis. This acquired disorder appears to be secondary to adsorption of factor X to the amyloid fibrils. [100, 101] In 1981, Greipp et al reviewed 30 cases of patients who had amyloidosis with factor X deficiency. [102] Modest deficiency of factor X was often associated with severe bleeding. In many cases, clinical bleeding could not be accounted for by deficiency of factor X alone, leading the authors to believe that coexistent hemostatic defects probably contributed to the bleeding. Testing with Russell viper venom may demonstrate an immunoglobulin G inhibitor that selectively inhibits factor X activation. [103]

Treatment of acquired factor X deficiency is difficult. In 2001, Boggio and Green reported that control of bleeding with plasma or prothrombin complex concentrates is not completely successful. [104] Smith and colleagues had similar problems in 2 patients, which led them to resort to daily therapeutic plasma exchange with concomitant administration of intravenous immunoglobulin and steroids. [103] This therapy produced a rapid increase in factor X levels, which controlled the bleeding, followed by gradual recovery of normal factor X levels and correction of coagulation times. Splenectomy eliminates the acquired factor X deficiency in amyloidosis, but control of operative bleeding may require recombinant factor VII.


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