Factor X deficiency is a disorder caused by too little of a protein called factor X in the blood. It leads to problems with blood clotting (coagulation).

When you bleed, the body launches a series of activities that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors. (Factor X is a coagulation factor.) Each factor's reaction triggers the next reaction. The final product of the coagulation cascade is the blood clot.

When certain coagulation factors are missing, the chain reaction does not take place normally. Factor X deficiency is often caused by a defect of the factor X gene that is passed through families (inherited). Bleeding ranges from mild to severe. Another cause of factor X deficiency is amyloidosis (a disorder in which protein fibers that can't dissolve deposit in tissues and organs and affect their function).

Women with this condition may have very heavy menstrual bleeding and bleeding after delivery. Newborn boys with the condition may have longer-than-normal 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

Treatment for the bleeding disorder is to get fresh frozen plasma or factor X concentrates into the blood during sudden (acute) episodes or before surgery. If the disorder is caused by amyloidosis, surgery is done to remove the spleen.

You can ease the stress of illness by joining a support group where members share common experiences and problems. See hemophilia - resources.

The outcome is usually good with mild disease or treatment.

Severe bleeding or sudden loss of blood (hemorrhage) can occur. The joints may get deformed in severe disease from many bleeds.

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 disorder that runs in families. There is no known way to prevent it.

Hoffman R, Benz E, Shattil S, Furie B, Cohen H. Hematology: Basic Principles and Practice. 4th ed. Philadelphia, Pa: Churchill Livingstone; 2004.

Sucker C, Hetzel GR, Grabensee B, Stockschlaeder M, Scharf RE. Amyloidosis and Bleeding: Pathophysiology, Diagnosis, and Therapy. Am J Kidney Dis. June 2006;47:947-955.

Takabe K, Holman PR, Herbst KD, Glass CA, Bouvet M. Successful perioperative management of factor X deficiency associated with primary amyloidosis. J Gastrointest Surg. March 2004;8:358-362.