Haemophilia
For the purpose of this document, the term “haemophilia” refers to FVIII / FIX
deficiency and other coagulation disorders.
Haemophilia is a blood clotting disorder in which one of the essential clotting factors is
deficient. Haemophilia A or classical haemophilia, is due to the deficiency of factor VIII.
Haemophilia B (or Christmas disease) is due to the deficiency of factor IX. As a result of
a deficiency of these clotting factors, formation of a blood clot is delayed and prolonged
bleeding may occur after minor injury or sometimes spontaneously. Haemophilia is a
problem of secondary haemostasis and is hereditary. Haemophilia A occurs in
approximately 1 in 8000 male births. Haemophilia B is less common and occurs in
approximately 1 in 30,000 male births. Haemophilia is an X linked disorder and affects
males almost exclusively, although females can be affected either by carrying the
haemophilia gene (sometimes referred to as symptomatic carriers) or by having both x
chromosomes affected by haemophilia mutations.
Haemophilia A is managed by either replacing the deficient factor VIII with a FVIII
concentrate or in mild cases using a drug called Desmopressin Acetate (DDAVP) to
increase the circulating factor VIII. Patients should have a proven response to DDAVP
before it is considered for treatment.
Haemophilia B is managed by replacing the deficient factor IX, with a FIX concentrate.
For further instructions see below – Administration of replacement therapy with Factor
concentrates.
Von Willebrand Disorder
Von Willebrand Disorder is the most common hereditary bleeding disorder and may
occur in up to 1% of the population. It is mostly an autosomal dominant disorder, but can
also be inherited as an autosomal recessive disorder. Patients with von Willebrand
Disorder either have diminished production of von Willebrand factor or produce von
Willebrand molecules that do not function normally – hence their platelets do not adhere
properly when blood vessels are injured and it takes longer for bleeding to stop. In some
patients, Factor VIII is also reduced, and blood clotting is impaired. Von Willebrand
Disorder is a problem of primary haemostasis.
Von Willebrand Disorder can in some cases be managed with DDAVP as described
above. DDAVP, as well as increasing the circulating factor VIII, also increases the
circulating von Willebrand factor. Depending on severity of the von Willebrand Disorder,
plasma concentrates which contain both von Willebrand factor and factor VIII may be
required as the replacement therapy.
For further instructions see below – Administration of replacement therapy with Factor
concentrates.