Bleeding Disorders Flashcards
what are causes of a failure of platelet plug formation
vascular
platelets
VWF
what are examples of vascular abnormalities that can cause problems
Marfan’s Syndrome
- have less collagen in their vessel walls
Vasculitis
- Henoch-Schonlein Purpura
what are acquired causes of thrombocytopenia
- reduced production
- marrow problem [along with pancytopenia] - increased destruction [if there was just a decrease in platelets]
what is thrombocytopenia
to few platelets
what are causes of platelet destruction
DIC = coag factors would fall too
Immune thrombocytopenic purpura (ITP) [autoimmune]
Hypersplenism = glandular fever, malignancy
what is the mechanism of destruction in ITP
antibodies stick to the platelet (IgG) which is then picked up by the spleen and removed
what drugs can cause an acquired platelet defect
aspirin
NSAID
apart from drugs, what else can cause an acquired platelet defect
renal failure
- urea builds up and effects the platelet function
what causes vWF deficiency - acquired
rare;
would be due to an antibody against vWF;
associated with hyperthyroidism
what causes vWF deficiency - hereditary
Autosomal dominant
reduction in vWF (more common) or reduced function in vWF (more severe)
Variable severity
what are causes of failure of a fibrin clot formation
DIC
Liver disease
[vitamin K deficiency leading to abnormal production of clotting factors]
Haemophilia
what tests results would suggest a multiple factor deficiency such as DIC or liver failure
prolonged PT AND APTT
where are all clotting factors made
the liver
what clotting factors require vitamin K
2 (prothrombin)
7
9
10
why do clotting factors need vitamin K
carboxylated by vitamin K = gives them a negative charge
w/out this they would not be attracted by the platelet plug to go to the area
what are sources of Vitamin K
diet - leafy green vegs [broccoli, sprouts]
where is vitamin K absorbed
upper intestine
what is required for vitamin K absorption
bile salts
- any gallstones in the gallbladder can lead to disruption
what are causes of Vit K deficiency
Poor dietary intake Malabsorption Obstructive jaundice Vitamin K antagonists (warfarin) Haemorrhagic disease of the newborn
what are babies given to avoid hemorrhagic disease of the newborn
IM Vit K injections
what is the definition of Disseminated Intravascular Coagulation (DIC)
Excessive and inappropriate activation of ALL the haemostatic system
what happens in DIC
Microvascular thrombus formation caused by platelet and fibrin clots
- causes end organ failure
THEN Clotting factor consumption as the body uses the factors up
- see bruising, purpura and generalised bleeding
what causes DIC
mass release of tissue factor
- can be due to sepsis, tumour, obstetric problems, hypocolaemic shock
what the lab findings in DIC
Prolonged PT
Prolonged APTT
Very High D-Dimer
Tx of DIC
treat the underlying cause
replacement therapy
- platelet transfusion
- plasma transfusions
- fibrinogen replacement
what is haemophilia
An X-linked, hereditary, life long disorder in which abnormally prolonged bleeding recurs episodically at one or a few sites on each occasion (called target joints)
what does X-linked mean
girls are carriers
boys are affected
what are the forms of haemophilia
Haemophilia A
- factor 8 deficiency
- most common
Haemophilia B
- factor 9 deficiency
what are common target joints
ankles
knees
elbows
what happens in target joins
bleed in, blood sits there, get iron, causing inflammation, new blood vessels form that are v fragile, can bleed again from these, more iron, more damage
untreated can lead arthropathy
what is important to remember in haemophilia
no abnormality of primary haemostasis
i.e. something like a paper cut would heal fine
what lab results are seen in haemophilia
PT = NORMAL
APTT = markedly PROLONGED
what are features of severe haemophilia
Recurrent Haemarthroses (ankle, knees, elbows)
Recurrent soft tissue bleeds
Prolonged bleeding after dental extractions, surgery and invasive procedures
