Factor IX ‘levels’ is the amount of factor IX we have in our blood. The number is usually given as a percentage. Normal levels range from 50 – 150%. If your levels are lower than this you will have been told you have Haemophilia B, or factor IX deficiency. How severe your haemophilia is depends on how low your levels are. A level less than 1% means you have severe haemophilia, and can bleed inside your body or joints for little or no apparent reason. Levels between 2-5% mean your haemophilia is moderate, and may only bleed if you are injured or have an operation. Mild haemophilia means your levels are between 5-50%, and again you may only bleed if you are injured or have an operation.
Answered by: Nurse