Disorders of Haemostasis #3 Flashcards
What are the three main causes of excessive bleeding in haemostatic disorders?
Thrombocytopenia (low platelet count)
Platelet function disorder
Defective coagulation factors
What is the inheritance pattern of Haemophilia A?
Haemophilia A is an X-linked recessive disorder caused by mutations in the FVIII gene on the X chromosome.
What is the typical clinical presentation of Haemophilia A?
Bleeds in load-bearing joints and muscles
Spontaneous haematuria or GI bleeding
Early childhood presentation when infants become mobile
In severe cases, spontaneous bleeding
What are the three types of Von Willebrand Disease (vWD)?
Type 1: Partial quantitative vWF deficiency (most common)
Type 2: Qualitative vWF defect
Type 3: Complete vWF deficiency (rare)
What coagulation factor is deficient in Haemophilia B?
Factor IX
What lab abnormalities are typical of vWD?
Prolonged APTT
Low FVIII activity
Low vWF levels
Functional platelet binding defects
Name symptoms commonly associated with vWD.
Mucous membrane bleeding (e.g., nosebleeds)
Menorrhagia
Easy bruising
Excessive bleeding post-trauma/surgery
List causes of thrombocytopenia.
Reduced bone marrow production
Increased platelet destruction or consumption
Drug-induced
Conditions like DIC, infections, or immune disorders
What are typical symptoms of thrombocytopenia?
Petechiae
Bruising
Mucosal bleeding (e.g. gums)
Haemorrhage post trauma
What lab features are seen in Disseminated Intravascular Coagulation (DIC)?
Prolonged PT and APTT
Low fibrinogen
Increased D-dimers/XDPs
Low platelets
Red cell fragments on blood film
What are key triggers of DIC?
Infections
Severe trauma
Malignancy
Obstetric complications
Liver failure
Which clotting factors are Vitamin K-dependent?
Factors II, VII, IX, and X
Name causes of Vitamin K deficiency.
Poor dietary intake
Liver dysfunction
Malabsorption (e.g. bile salt absence)
Antibiotic use
GI surgery
What is the genetic defect in Factor V Leiden?
Mutation at Arg506 that prevents inactivation by APC, leading to increased FVa activity and thrombosis risk.
Name three types of anti-thrombotic therapies.
Warfarin – inhibits Vitamin K factor production
Heparin – enhances antithrombin activity
Aspirin – inhibits platelet aggregation
What proteins are involved in Protein C/Protein S deficiency?
Protein C inactivates FVa and FVIIIa; Protein S acts as its cofactor. Deficiency in either increases thrombotic risk.
