Factor X Deficiency
What is factor X deficiency?
People with factor X (10) deficiency (sometimes called Stuart-Prower deficiency) have low levels of factor X in their blood. Factor X helps activate a protein called prothrombin (factor II), which is needed to form a stable blood clot.
Recently, an international organization (International Society on Thrombosis and Hemostasis) proposed a classification of factor X deficiency severity based upon factor activity and associated symptoms, with a few exceptions.
- Mild (> 40% activity): Patients are mostly asymptomatic, but might have problems with bleeding during trauma, a surgical procedure or with pregnancy/delivery
- Moderate (10-40% activity): Patients may have mild spontaneous bleeding, or bleeding triggered by trauma, surgery, or pregnancy/delivery
- Severe (< 10% activity): Patients may have spontaneous, severe, and even life-threatening bleeding
What causes it?
Factor X deficiency is inherited from both parents. It can also develop as a person gets older. It is rare and occurs in 1 in every 500,000 to 1 million people.
What are the symptoms?
The level of factor X in the blood does not always match the severity of bleeding. Symptoms include:
- Umbilical stump bleeding at birth (for those severely affected)
- Nose bleeds
- Mouth bleeds
- Easy bruising
- Swelling, pain, or warmth around a joint
- Inability to straighten or bend a joint normally
- Headache or neck ache
- Drowsiness or loss of consciousness
- Upset stomach
- Vomit that is black and syrupy or bright red
- Sensitivity to light
- Weakness, tingling, or pain in the arms or legs
- Difficulty with urination or bowel movements
- Bleeding after surgery or trauma
- In women, heavy menstrual bleeding
How is it diagnosed?
Factor X deficiency is diagnosed after finding screening tests that identify prolonged prothrombin time (PT) and activated partial thromboplastin time (aPTT) then by following up to determine that factor X activity is lower than normal. These results should be confirmed by a specialized health care provider.
How is it treated?
Bleeding episodes may need to be treated. There are blood-derived products that include factor X but no specific factor concentrates are available. Excessive menstrual bleeding in women with factor X deficiency may be controlled with hormonal contraceptives (birth control pills), intra-uterine devices (IUDs), or antifibrinolytic drugs.