What does severity mean?

There are three types of haemophilia: mild, moderate and severe. The level of severity depends on how much clotting factor VIII (8) or IX (9) is in the person’s blood naturally.  A person with haemophilia will have the same level of severity their whole life, e.g. someone with severe haemophilia will always have severe haemophilia. Within a family, males will also inherit the same level of severity, e.g. if a grandfather has severe haemophilia and his grandson has inherited haemophilia, his grandson will also have severe haemophilia. However, this is not the same for females. For example, a girl whose father has severe haemophilia may have the same factor levels and symptoms as a girl whose father has mild haemophilia.

For a person who doesn’t have haemophilia, the range of factor VIII (8) and factor IX (9) in their blood is usually between 50% and 200%

Mild haemophilia

5 – 40% of normal clotting factor
  • Usually only have bleeding problems after having teeth taken out, surgery or a bad injury or accident
  • Might never experience a bleeding problem.
 

Moderate haemophilia

1 – 5% of normal clotting factor
  • Might have bleeding problems after having teeth taken out, surgery or a bad injury or accident
  • Might have a bleed about once a month
  • Rarely have a bleed for no obvious reason.
 

Severe haemophilia

Less than 1% of normal clotting factor
  • Often have bleeds into joints, muscles and soft tissues
  • Can have bleeds for no obvious reason, as well as after surgery, dental work or injuries including minor bumps or knocks
  • Might have a bleed once or twice a week

Date last reviewed: 21/06/2012