Factor X deficiency is a disorder that causes abnormal blood clotting (coagulation), resulting from a shortage of a plasma protein called factor X.

Normal blood coagulation is a complex process involving as many as 20 different plasma proteins known as blood coagulation factors. A series of complex chemical reactions using these factors takes place very rapidly to form an insoluble protein fibrin that stops bleeding.

When certain coagulation factors are deficient or missing, the chain reaction does not take place normally. Factor X deficiency is often caused by an inherited defect of the factor X gene, and bleeding ranges from mild to severe. Another cause of factor X deficiency is amyloidosis (a disorder in which insoluble protein fibers deposit in tissues and organs, impairing their function).

Women with this condition may have severe menstrual bleeding and bleeding after delivery. Newborn boys with the condition may have prolonged bleeding after circumcision.

Factor X deficiency affects 1 out of every 500,000 people.

• Nose bleeds
• The loss of blood into joints
• Muscle bleeding
• Mucous membrane bleeding

• Prolonged prothrombin time
• Prolonged partial thromboplastin time
• Low factor X activity
• Normal thrombin time

The bleeding disorder is corrected by infusions of fresh frozen plasma or factor X concentrates during acute episodes or in preparation for surgery. Treatment for factor X deficiency related to amyloidosis involves surgical removal of the spleen.

The stress of illness can often be helped by joining a support group where members share common experiences and problems. See hemophilia - resources.

The outcome is usually good with mild disease or with adequate therapy.

Severe bleeding or hemorrhage can occur. Joint deformities may result from repeated bleeds in severe disease.

Call your health care provider, go to the emergency room, or call the local emergency number (such as 911) if you have an unexplained or severe loss of blood.

This is a rare inherited disorder. There is no known way to prevent it.