bleeding disorders Flashcards
what are the causes of bleeding?
- vascular disorders
- platelet disorders (thrombocytopenia, defective function)
- defective coagulation (inherited, acquired)
what alters the pattern of bleeding?
- vascular and platelet causes, bleeding into mucous membranes and skin
- coagulation disorders, bleeding into joints and soft tissues
what is vascular bleeding?
problems with vessel wall
what are the causes of vascular bleeding?
- inherited: hereditary haemorrhagic telangiectasia, ehlers-danlos syndrome
- acquired: scurvy, steroids, senile
what is thrombocytopenia?
low platelets (<150)
when do symptoms of thrombocytopenia occur and what are the symptoms?
when platelets are <10 and the syptoms are epistaxis, GI bleeds, menorrhagia, bruising
what causes thrombocytopenia?
- inherited causes (rare)
- acquired causes (common), eg: ITP, drug-related, DIC
what are the treatment options if bleeding or platelets <20?
1) steroids and/or intravenous immunoglobulins
2) thromboitein agonists
3) immunosuppression
4) splenectomy
what causes coagulation disorders?
- due to defect in the coagulation cascade
- inherited causes (rare)
- acquired causes (common)
what are the different tests of coagulation?
- APTT = activated partial thromboplastin time
- PT = prothrombin time
- TT = thrombin time
- fibrinogen level - clotting factor assay
- bleeding time (no longer done)
- D-dimers = breakdown products of fibrin clot
what is haemophilia A?
deficiency of factor VIII
what is haemophilia B?
deficiency of factor IX (also known as christmas disease)
what type of diseases are haemophilia?
X-linked so only affect males
what are clinical features of haemophilia?
- spontaneous bleeding into joints and muscles
- unexpected post-operative bleeding
- chronic debilitating joint disease
- family history in majority of cases
how do you diagnose haemophilia?
- prolonged APTT (test factors VIII, IX, XI, XII in the intrinsic pathway)
- normal PT (test factors II, V, VII, X) in the extrinsic pathway
- low factor VIII or IX levels (<1% = severe, 1-5% = moderate and >5% = mild haemophilia)
what are the treatments of haemophilia?
- historic treatments - fractionated human plasma
- HIV and Hepatitis C infection (and risk of vCJD)
- current treatment - infusions of recombinants factor VIII or factor IX to 50-100% of normal
- prophylactic treatment has revolutionised management of haemophilia patients
what type of disease is von Willebrand disease?
autosomal dominant
what is von Willebrant factor?
large multimeric protein that carries factor VIII in the blood and it binds platelets to endothelial collagen
what is von Willebrand disease?
deficiency of von Willebrand factor and FVIII in plasma
what are the symptoms of von Willebrand disease?
- mucocutaneous bleeds
- nosebleeds
- menorrhagia
what are the tests for diagnosing von Willebrand disease?
- prolonged APTT
- normal PT
- low vWF antigen level and/or vWF function
- low factor VIII level
- prolonged bleeding time
- defective platelet function
how do you treat von Willebrand disease?
treatment with desmopressin, anti-fibrinoytics and plasma products
what stimulates release of vWF from Weibel-Palade sotrage bodies from endothelial cells?
DDAVP
what are acquired disorders of coagulation?
non-inherited causes of increased bleeding
what are the acquired disorders of coagulation?
- liver disease
- vitamin K deficiency
- disseminated intravascular coagulation (DIC)
how does the acquired disorders of coagulation affect liver disease?
- deficient synthesis of clotting proteins
- impaired platelet function and fibrinolysis
how does the acquired disorders of coagulation affect vitamin k deficiency?
- infants who do not receive vitamin k at birth
- malabsorption due to jaundice
how does the acquired disorders of coagulation affect disseminated intravascular coagulation (DIC)?
- release of pro-coagulant material into circulation
- results in consumption of clotting factors
- causes both bleeding and thrombosis to occur
what is meningococcal DIC?
- prolonged PT, APTT, TT
- low fibrinogen, low platelets
how do you know if someone has meningococcal DIC?
they have raised D-dimers or FDPs
what causes DIC?
cancer, sepsis, obstetric diasters
what is latrogenic?
overdose of anti-coagulant drugs
what are the types of anticoagulants?
- heparin = used to treat MIs, PEs, DVTs
- warfarin = used to treat PEs, DVTs, AF, prosthetic valves
- DOACs = direct oral anti-coagulants (direct thrombin inhibitors, factor Xa inhibitors)
what is vitamin K needed for?
required for carboxylation of factors II, VII, IX, X
what inhibits vitamin K?
warfain
what causes vitamin k deficiency?
- malabsorption of vitamin k
- biliary obstruction
- haemorrhagic disease of the newborn
