3: Bleeding disorders Flashcards
What are some causes of problems with secondary haemostasis?
Single factor deficiencies - Haemophilia A & B
Multiple factor deficiencies - Vitamin K deficiency, liver disease, DIC
note that DIC is a cause of problems with both primary and secondary haemostasis (because it drains platelets AND clotting factors)
What are some causes of problems with primary haemostasis?
VASCULAR: less available collagen (ageing), Vit C deficiency, steroids, Henoch Schonlein purpura (vasculitis)
PLATELETS: bone marrow suppression, renal failure, autoimmune thrombocytic purpura, DIC, hypersplenism
VON WILLEBRAND DISEASE
What is a
reduced
increased
number of platelets called?
Reduced platelets - thrombocytopaenia
Increased platelets - thrombocytosis
Which drugs reduce the function of platelets?
Anti-platelets e.g aspirin, clopidogrel, ticagrelor
NSAIDs
What is Von Willebrand’s disease?
vWF deficiency
Von Willebrand’s disease is more commonly diagnosed in (men / women).
Why?
women
menorrhagia presents early
Which vasculitis, seen in children, causes abnormal bleeding?
HSP
Where should you look for a purpuric rash first?
Why?
Lower limbs
Oncotic pressure (gravity) pushes blood out of capillaries into compartments of lower limb
Where should you look for haemorrhages in a patient with abnormal bleeding?
Skin
Mouth
Eyes
What are some acquired causes of thrombocytopaenia?
Bone marrow pathology e.g malignancy
DIC (widespread clotting uses up all your platelets and clotting factors)
Autoimmune disease (autoimmune thrombocytopaenic purpura)
Renal failure (uraemia causes platelet destruction)
What are autoimmune diseases causing
a) vessel dysfunction
b) platelet destruction
causing abnormal bleeding?
a) HSP (vasculitis)
b) ATP
Why can hypersplenism cause platelet destruction?
Overactive haemolysis
Which drugs are designed to cause platelet dysfunction?
How do they work?
Anti-platelets e.g aspirin, clopidogrel, ticagrelor
Block thromboxane A2
Why does renal failure cause platelet dysfunction?
Build up of toxins e.g urea
What is the mode of inheritance of Von Willebrand’s disease?
Autosomal dominant
Apart from promoting platelet aggregation, what does vWF do?
Carries Factor XIII around
So deficiency also impacts coagulation
Low levels of circulating ___ is the most common reason for failure of haemostasis.
platelets
i.e thrombocytopaenia
What is prothrombin also known as?
Factor II
just to make things more confusing
In which condition are clotting factors and platelets used up to the point that they are deficient?
DIC
Where are clotting factors produced?
Liver
Problems with which organ impact coagulation?
Liver
where clotting factors are produced
Which vitamin is required to produce clotting factors?
Vitamin K
Which clotting factors are deficient in
Haemophilia A
Haemophilia B?
Haemophilia A - VIII
Haemophilia B - IX
Which clotting factors require Vitamin K to be activated?
II, VII, IX and X
Which clotting factors are inhibited by warfarin therapy?
II, VII, IX and X
Which clotting time is used to measure warfarin response?
Which clotting factors does warfarin inhibit?
What is required to produce these factors in the liver?
PT
II, VII, IX and X
Vitamin K
Clotting factors are deficient in ___ failure.
liver failure
___ _ deficiency causes abnormal bleeding.
Vitamin K
required for production of factors II, VII, IX and X in the liver
Where is Vitamin K absorbed?
Small intestine
What is required for Vitamin K to be absorbed in the small intestine?
Bile salts
Given that Vitamin K is absorbed in the small intestine using bile, what GI conditions can cause Vitamin K deficiency?
Malabsorption - Crohn’s disease, resection, bacterial overgrowth
Obstructive jaundice - cholecystitis, pancreatic Ca
Which drug acts against Vitamin K?
Warfarin
Vitamin K can be used to reverse the effects of which drug?
Warfarin
Why are babies given a Vitamin K injection at birth?
To prevent bleeding caused by temporary Vit K deficiency, which is quite common
haemorrhagic disease of the newborn
What is DIC?
Disseminated intravascular coagulation
Massive, inappropriate activation of haemostasis and fibrinolysis
Using up all your platelets and clotting factors
Which causes deficiencies –> tendency for abnormal bleeding
Apart from platelet / clotting factor deficiency, what does massive thrombosis in DIC cause?
End organ damage
because all your vessels are occluded
Apart from abnormal bleeding, what does DIC cause?
End organ damage
because thromboses occlude blood vessels
Which enzyme breaks down fibrin?
Plasmin
What are some causes of DIC?
Massive trauma
Sepsis
Obstetric emergencies e.g toxic shock syndrome, placental abruption
Malignancy
Hypovolaemic shock
In which type of sepsis is DIC especially common?
Meningococcal sepsis
How is DIC treated?
Treat underlying cause
Replace deficencies
platelet transfusions
plasma transfusions (for clotting factors)
fibrinogen replacement
What is the mode of inheritance of haemophilia?
X-linked recessive
Haemophilia is only expressed in (males / females).
males
because it is X-linked recessive
Where does bleeding occur in haemophilia?
Skin
Mouth
Eyes
Into joints (haemarthrosis)
Why does haemarthrosis recur in people with haemophilia?
Blood in joint
> Iron in joint (irritant)
> Inflammation
> Recurrent bleeding
Haemophilia is a problem with (primary / secondary) haemostasis.
secondary haemostasis
How is haemophilia treated?
Factor VIII / IX injections
How regularly are haemophiliacs given clotting factor injections?
Every 2 - 3 days
Which clotting time is abnormal in haemophilia?
APTT
because it measures XIII/IXa action (which are deficient in haemophilia A/B)
In which joints does haemarthrosis occur in haemophilia?
Ankles
Knees
Elbows
(also: quads, iliopsoas)
In multiple factor deficiencies, which clotting times are prolonged?
PT
APTT
i.e both of them
Name three reasons for multiple factor deficiency.
Liver disease
Vitamin K deficiency
DIC
Name a reason for single factor deficiency.
Haemophilia
