Bleeding Disorders Flashcards
What are the main areas of haemostasis affected to cause bleeding disorders?
Primary and secondary haemostasis
What is the function of von Willebrand factor?
Acts as glue to allow platelets to stick to collagen
What are the causes of failure to form a platelet plug?
Vascular abnormalities, thrombocytopenia, platelet function defects, vWF deficiency
What are the causes of vascular abnormalities?
Hereditary
Acquired = Vasculitis (HSP), ageing process (loss of collagen)
What are the causes of thrombocytopenia?
Hereditary = rare Acquired = reduced production, increased destruction (more common)
What tends to cause decreased platelet production?
Marrow problems = tends to cause pancytopenia
What tends to cause increased platelet destruction?
Coagulopathy = disseminated intravascular coagulation
Autoimmune = most common cause, immune thrombocytopenic purpura
Hypersplenism
What are the causes of platelet functional deficits?
Hereditary = rare Acquired = drugs (aspirin, NSAIDs), renal failure
What is the most common cause of primary haemostatic failure?
Thrombocytopenia = usually acquired
What are the causes of vWF deficiency?
Acquired = uncommon Hereditary = common (1 in 1000), autosomal dominant, mostly mild
Are multiple clotting factor deficiencies usually acquired or hereditary?
Acquired = more likely that a single clotting factor deficiency will be hereditary
What are the causes of multiple clotting factor deficiencies?
Liver failure = liver produces all clotting factors
Vitamin K deficiency/warfarin therapy
Complex coagulopathy
What clotting factors would be affected by vitamin K deficiency/warfarin therapy?
Factors II, VII, IX and X
Where are coagulation factors synthesised?
In hepatocytes of the liver
What is the function of vitamin K?
Carries out final carboxylation of factors II, VII, IX and X
What are some sources of vitamin K?
Diet = leafy green vegetables
Synthesised in upper bowel by bacteria
Where is vitamin K absorbed?
In the upper intestine = requires bile salts
What are some causes of vitamin K deficiency?
Dietary insufficiency, malabsorption, obstructive jaundice, vitamin K antagonists, haemorrhagic disease of the newborn
What is disseminated intravascular coagulation?
Excessive and inappropriate activation of the haemostatic system
What areas of haemostasis are affected by disseminated intravascular coagulation?
Primary and secondary haemostasis plus fibrinolysis
What occurs in disseminated intravascular coagulation?
Microvascular thrombus formation = end organ failure
Clotting factor consumption = bruising, purpura, generalised bleeding
High levels of D-dimers
What are some causes of disseminated intravascular coagulation?
Sepsis, obstetric emergencies, malignancy, hypovolaemic shock
What is the treatment of disseminated intravascular coagulation?
Treat underlying cause and give replacement therapy while waiting for definitive diagnosis = platelet and plasma transfusion, fibrinogen replacement
What are haemophilias?
X-linked hereditary disorders = cause abnormally prolonged bleeding that recurs episodically at one or a few sites
