Hameostasis Flashcards
What is it called when platelets are reduced in number?
Thrombocytopenia
List two causes of impaired thrombocyte production.
-Leukemia
-B12 deficiency
Give two examples of conditions where you will find accelerated thrombocyte clearance.
-Immune thrombocytopenia purpura (ITP)
-Disseminated intravascular coagulation (DIC)
Give a third reason you can find thrombocytopenia
Pooling and destruction in an enlarged spleen
Which 3 drugs commonly caused impaired thrombocyte function?
-Aspirin
-NSAIDs
-Clopidogrel
What does aspirin do?
Irriversibly blocks COX which leads to decreased production of thromboxane A2.
How does clopidogrel work?
Irreversibly blocks the ADP receptor P2Y12 on platelets.
What two functions does VWF have in haemostasis?
-Binding to collagen and capturing platelets
-Stabilising factor VIII
What is the inheritance pattern in VWF disease?
Is usually hereditary with autosomal inheritance pattern.
Which types of VW disease lead to deficiency of VWF?
Type 1 or 3
Which types of VWD lead to normal VWF production but with impaired function?
Type 2
What is the overall negative effect of a lack of VWF in haemostasis?
Inability to form the platelet plug
What are the clinical features pf disorders of primary haemostasis?
Immediate prolonged heavy bleeding.
Easy spontaneous bruising
What are petechiae and purpura caused by and which one does not blanch when pressure is applied?
They are caused by bleeding under the skin and purpura do no blanch when pressure is applied.
What is a common feature of thrombocytopenia?
Petechiae
In severe VWD what can the bleeding pattern resemble?
Haemophilia due to low FVIII
What is the bleeding called when the ‘mark’ is greater than 10mm?
Ecchymosis
What are the tests for disorders of primary haemostasis?
-Platelet count, platelet morphology
-PFA100
-Assays of VWF
-Clinical observation
What treatment can you give in mild VWF disorders?
Desmopressin (DDAVP)
What is haemophilia A caused by?
Factor VIII deficiency
What is haemophilia B caused by
Factor IX deficiency
What are the acquired causes of coagulation factor production deficiencies?
-Liver disease
-Anticoagulant drugs (Warfarin, DOACs)
What is haemophilia?
inability to generate fibrin to stabilise the platelet plug
What is the hallmark of haemophilia?
Haemarthrosis (spontaneous joint bleeding)
What should be avoided in patients with haemophilia?
Intramuscular injections
What is a common cause of a coagulation disorder which results in increased consumption and depletion of coagulation factors?
Disseminated intravascular coagulation
Explain the differences in the bleeding patterns between Platelet/Vascular defects and coagulation defects
Platelet/Vascular:
-superficial bleeding into skin, mucosal membranes.
-Bleeding immediate after injury
Coagulation:
-Bleeding deep into tissues, muscles, joints
-Delayed, but severe bleeding after injury
What does Prothrombin time measure?
the extrinsic pathway
What does the activated partial thromboplastin time measure?
Measures the intrinsic pathway
What drug treatment can be used in haemophilia A to mimic factor VIII?
Emicizumab
What are the three contributary factors to thrombosis called?
Virchow’s triad:
-Blood, dominant in venous thrombosis
-Vessel wall, dominant in arterial thrombosis
-Blood flow, contributes to both arterial and venous thrombosis
What term is used to refer to an increased risk of venous thrombosis?
Thrombophilia
