Haemophilia severity

How severe is haemophilia?

There are three levels of severity in haemophilia:

mild
moderate
severe

The severity of haemophilia depends on the amount of clotting factor in the person’s blood.

Can a person’s factor level change?

A person with haemophilia will usually have the same level of severity over their lifetime, eg a person with severe haemophilia will always have severe haemophilia. Within a family, males with haemophilia will also nearly always have the same level of severity, eg if a grandfather has severe haemophilia and his grandson has inherited haemophilia, his grandson will also have severe haemophilia. However, factor levels in females affected by haemophilia are unpredictable and severity can vary between females and other family members.

It may take some time after birth to confirm a child’s factor level while their factor levels stabilise. Factor VIII (8) levels can also change for females with pregnancy and hormonal medications such as the contraceptive pill and as they grow older. Factor IX (9) levels rarely change in people with haemophilia B.

Can a female have bleeding problems with a normal factor level?

Some females who carry the gene alteration and have factor levels at the lower end of normal (40-50%) may also experience abnormal bleeding. If further investigation indicates the bleeding is related to haemophilia, they will be treated as having mild haemophilia and diagnosed as symptomatic haemophilia carriers.

What is a normal factor level?

The normal level of factor VIII or IX in a person’s blood is between 50% and 150%.

What to expect if you have haemophilia
Mild haemophilia5% – 40% of normal clotting factor level	Likely to bruise easily and have prolonged bleeding after minor cuts Likely to have bleeding problems after having teeth taken out, surgery or medical procedures that cut the skin or a bad injury or accident. Females might have heavy menstrual bleeding (heavy periods) Females may have bleeding problems with childbirth. Otherwise might only have bleeding problems requiring medical attention very occasionally.
Moderate haemophilia1% – 5% of normal clotting factor level	Likely to bruise easily and have prolonged bleeding after minor cuts May have bleeding problems after minor injuries, such as sporting injuries Likely to have bleeding problems after surgery, medical or dental procedures that cut the skin or a bad injury or accident Females likely to have heavy menstrual bleeding (heavy periods) Females sometimes have bleeding problems with childbirth Occasionally have a bleed for no obvious reason.
Severe haemophiliaLess than 1% of normal clotting factor level	Likely to bruise easily and have prolonged bleeding after minor cuts Often have bleeds into joints, muscles and soft tissues Can have bleeds for no obvious reason (‘spontaneous bleeds’), as well as after surgery, medical or dental procedures that cut the skin and injuries including minor bumps or knocks. Females likely to have heavy menstrual bleeding (heavy periods) Females likely to have bleeding problems with childbirth.

Please note: this table is a guide only.

Sources

How severe is haemophilia?

Can a person’s factor level change?

Can a female have bleeding problems with a normal factor level?

What is a normal factor level?

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