What is factor X deficiency?

Updated: Jul 31, 2019
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

Clotting factor X, or Stuart-Prower factor, is a vitamin K–dependent serine protease that serves as the first enzyme in the common pathway of thrombus formation. Factor X deficiency is a bleeding disorder that can be inherited or acquired. This disorder is one of the world's most rare factor deficiencies.

Inherited factor X deficiency is autosomal recessive, with heterozygotes most often remaining asymptomatic or having only a mild bleeding tendency. [1] Homozygous individuals may experience hemorrhagic symptoms, including easy bruising, hematuria, soft-tissue hemorrhages, hemarthroses, recurrent epistaxis, and menorrhagia. [2] Pedigree analysis of patients with congenital factor X deficiency often reveals consanguinity.

Acquired factor X deficiency can be caused by severe liver disease, vitamin K deficiency, or anticoagulant drugs such as warfarin. Factor X deficiency has also been reported in association with a variety of medical conditions (eg, systemic light-chain amyloidosis, [3] atypical chronic lymphoid leukemia [5] ).

Treatment of factor X deficiency is individualized, but restoring circulating factor X levels to 10-40% of normal is usually adequate. Additionally, in patients with acquired factor X deficiency, treatment of the underlying cause may resolve the disorder.  Treatment options include factor X concentrate, fresh frozen plasma, and prothrombin complex concentrates (PCCs). Vitamin K is ineffective in hereditary factor X deficiency but may be useful in certain acquired cases. (See Treatment and Medication.)

For patient education information, see Bruises and Blood Spots Under the Skin and Blood in the Urine.


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