What Is Factor X?

Medically Reviewed by Dan Brennan, MD on May 10, 2021

Factor X is a protein in your blood that helps with clotting. Blood clotting is important because that is what helps you to stop bleeding when you get a cut or bruise. Factor X deficiency is a genetic disorder when you are born without this protein. You can also develop the condition later in life.

Other names for factor X deficiency include: 

  • Stuart-Power factor deficiency, 
  • F10 deficiency, 
  • Congenital Stuart factor deficiency 
  • Congenital factor X deficiency

Symptoms of Factor X Deficiency

Factor X deficiency is a condition that leads to a bleeding disorder. The symptoms of factor X deficiency include:

The severity of factor X deficiency varies from person to person. Your body still produces 40% or more of the normal amount of factor X in mild cases. You may have no symptoms or only very minor ones. 

Your body produces 10% to 40% of the usual amount of factor X if you have a moderate case of the deficiency. It is considered severe if you have less than 10% of the normal amount of factor X.

How Common Is Factor X Deficiency?

Factor X deficiency is a rare disorder. It only occurs in 1 out of every 500,000 to 1 million people. People of any gender have an equal chance of getting it.

What Causes Factor X Deficiency?

Genes. Some people inherit factor X deficiency. This is called congenital factor X deficiency.

Congenital factor X deficiency is caused by a mutation to the F10 gene. This gene is a protein-coding gene that controls the process that creates factor X in your blood. Your body produces less of the factor when a mutation occurs. This leads to difficulty with blood clotting.

Genetic factor X deficiency means that both of your parents have at least one copy of the mutated gene and have both passed one on to you. They are just carriers if each parent has only one copy of the gene. This means they would not have any symptoms.

Certain conditions. Acquired factor X deficiency is when you have not inherited it. Causes of acquired factor X deficiency include:

How Do Doctors Diagnose Factor X Deficiency?

Doctors diagnose factor X deficiency in the following ways:

  • Take your medical history, including a family history
  • Do tests that show how quickly your blood clots
  • Do tests to measure how much factor X your body produces
  • Do genetic testing to determine if you have the mutation that causes factor X deficiency

Treatments for Factor X Deficiency

Cogadex. Doctors typically treat excess bleeding when it happens. The main treatment for a bleeding episode is a drug called Cogadex. It is a version of factor X that people with factor X deficiency can take to either prevent a bleeding episode or stop bleeding after it has already started. 

Your doctor may also recommend this drug if you are going to have surgery and you have factor X deficiency.

PPC. Another option for treatment is promotherin plasma concentrate (PPC). This product contains factor X along with factors II, VII, and IX. But most people only lack one of these clotting factors. So this treatment may be less ideal than Cogadex. Using PPC may also increase the risk of blood clots due to excess amounts of the wrong clotting factor.

Plasma. Treatment with fresh frozen plasma is another option for a bleeding episode. There are some minor risks, like viral infections. However, doctors screen blood to lower this risk.

Antifibrinolytic agents. Your doctor may recommend other treatments like nosebleed powder or antifibrinolytic agents for mild symptoms. These are drugs that help your blood to clot.

Your doctor may recommend a supplement if your factor X deficiency is caused by a lack of vitamin K. They may recommend genetic testing or counseling before you decide to have children if factor X deficiency runs in your family.

People with severe clotting factor deficiencies should generally avoid high impact activities where the potential for injury is greater.

Other Blood Clotting Factors

There are 12 other factors in addition to X that are important in blood clotting. All of them have Roman numerals and are numbered I to XIII. Each one represents a different protein involved at some stage of blood clotting or coagulation.

You can have a deficiency in many of the other 12 factors. Each one has a different name. But the symptoms may be similar. All of the factor deficiencies cause excessive bleeding.

WebMD Medical Reference



GARD: "Factor X deficiency."

GeneCards: "F10 Gene (Protein Coding)."

MedlinePlus: "Factor X deficiency."

NATIONAL CANCER INSTITUTE: "antifibrinolytic agent."

National Hemophilia Foundation: "FACTOR X (Stuart-Prower Factor) DEFICIENCY."

NORD: "Factor X Deficiency."

StatPearls: "Physiology, Coagulation Pathways."


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