Bleeding Disorders Flashcards
causes of failed platelet plug formation
vascular problem – decreased collagen
platelet problem – decreased numbers/function
VWF – decreased production/function
examples of vascular diseases that can cause failed platelet plug formation
marfans syndrome
– have less collagen in their vessel walls
vasculitis
– Henoch- Schonlein purpura
what is honoch schonlein purpura
IgA vasculitis
commonly occurs in children
causes vessels in the skin, joints, bowel and kidney to leak
what is thrombocytopenia
too few platelets
congenital cause of thrombocytopenia
Fanconi’s anaemia
which two mechanisms can lead to acquired thrombocytopenia
- reduced production
2. increased destruction
what causes acquired decreased production of platelets
marrow failure megaloblastic anaemia leukaemia myeloma myelofibrosis aplastic anaemia
what causes increased destruction of platelets
coagulopathy – disseminated intravascular coagulation
autoimmune – immune thrombocytopenic purpura (ITP)
hypersplenism
In children, what does immune thrombocytopenic purpura (ITP) often follow
viral infection
- rapid onset of purpura that is usually self limiting
who is ITP most commonly seen in
young women
features of ITP
often occurs with other autoimmune disorders e.g. SLE/thyroid disease
fluctuating course with easy bruising, epistaxis and menorrhagia
1st line treatment of ITP
oral corticosteroids
when might IV IgG be used in a patient with immune thrombocytopenic purpura
when a rapid rise in platelets is required e.g. before surgery
2nd line treatment of ITP
splenectomy
drugs that can cause platelet functional defects
aspirin
NSAIDS
how does renal failure cause an acquired platelet defect
urea builds up and effects platelet function
what causes an acquired VWF deficiency
antibody formation against VWF
- rare
- associated with hyperthyroidism
what causes a hereditary VWF deficiency
Type 1 - autosomal dominant, partial decrease in VWF
Type 2- abnormal VWF
Type 3- autosomal recessive, complete lack of VWF
what can cause failure of fibrin clot formation
multiple clotting factor deficiencies
- Disseminated intravascular coagulation
- vitamin K deficiency
- liver disease
- usually acquired
single clotting factor deficiency
- haemophilia
- usually hereditary
which clotting factors require vitamin K for formation
II (prothrombin), VII, IX, X
what is clotting factor II also know as
prothrombin
where are all clotting factors made
the liver
why do clotting factors need vitamin K
they are carboxylated by vitamin K – gives them a negative charge
without this they would not be attracted by the platelet plug
what drug causes vitamin K deficiency
warfarin
