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
causes of vitamin K deficiency
poor dietary intake malabsorption obstructive jaundice warfarin haemorrhage disease of the new born
dietary sources of vitamin K
leafy green veg e.g broccoli, spinach, kale
where is vitamin K absorbed
upper intestine
what is required for vitamin K absorption
bile salts
- gallstones in the gallbladder can lead to disruption
what are babies given to prevent haemorrhagic disease of the new born
IM Vit K
what test results would suggest a multiple factor deficiency
prolonged PT + APTT
what is disseminated intravascular coagulation
excessive + inappropriate activation of the haemostatic system
- primary, secondary + fibrinolysis
what causes DIC
mass release of tissue factor can be due to - sepsis - tumour - trauma - surgery - obstetric problems - hypovolaemic shock
effects of DIC
microvascular thrombus formation caused by platelet + fibrin clots
- causes end organ failure
clotting factor consumption as the body uses the factors up
- see bruising, purpura + generalised bleeding
secondary activation of fibrinolysis
- production of FDP
lab findings in DIC
prolonged PT + APTT
high D dimer
treatment of DIC
treat underlying cause
replacement therapy
- platelet transfusion
- fibrinogen replacement - cryoprecipitate
what is haemophilia
X linked hereditary disorder in which abnormally prolonged bleeding recurs episodically at one or a few sites – called target joints
how is haemophilia inherited
X linked
- girls are carriers
- boys are affected
what are the forms of haemophilia
Haemophilia A
Haemophilia B
what factor is deficient in haemophilia A
factor VIII
- most common
what factor if deficient in haemophilia B
factor IX
common target joints
ankles
elbows
knees
what happens in target joints
bleeding, blood pools there, iron causes inflammation, new blood vessels form that are fragile
– can bleed again, more iron = more damage
untreated can lead to arthropathy
features of haemophilia
recurrent haemathroses
recurrent soft tissue bleeds
prolonged bleeding after dental extractions, surgery and invasive procedures
what is important to remember about haemophilia
no problems with primary haemostasis- only secondary is affected
therefore small bleeds like paper cuts would heel fine
lab results in haemophilia
NORMAL PT time
APTT - markedly PROLONGED
Treatment of haemophilia A
IV recombinant factor VIII
what can be given in mild haemophilia A
desmopressin - raises factor VIII levels
treatment of haemophilia B
IV facor IX
desmopressin is ineffective
treatment of VWF disease
tranexamic acid
desmopressin
who gets DIC
hospitalised patients with IV lines
