Bleeding disorders Flashcards
what is haemophilia
an X linked hereditary disorder in which abnormally prolonged bleeding recurs episodically at oe or a few sites on each occasion
what is Haemophilia A
factor VIII deficiency
what is haemophilia B
factor IX deficiency
describe the features of haemophilia
no abnormality of primary haemostasis
bleeding from medium to large blood vessels
mild moderate and severely affected families depending on factor VIII/IX level
what does prothrombin time screen for
Tissue factor/VIIa
what does APTT screen for
VIII/IXa
what does APTT stand for
activate partial thromboplastin time
what are the clinical features of severe haemophilia
recurrent haemarthroses
recurrent soft tissue bleeds-bruising in toddlers
prolonged bleeding after dental extractions, surgery and invasive procedures
what does heparin do
prevents activation factors 2,9,10,11
warfarin
affects synthesis of factors 2,7,9,10
describe blood test abnormalities in haemophilia
APTT prolonged PT normal
what is thrombophilia
familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis
potential mechanisms of thrombophilia
increase in coagulation activity
decrease in fibrinolytic activity
decrease in anticoagulant activity
name some of the naturally occurring anticoagulants
Serine protease inhibitors
Protein C and Protein S
name some hereditary thrombophilia
Factor V Leiden Prothrombin 20210 mutation Antithrombin deficiency Protein C deficiency Protein S deficiency
if you have a hereditary thrombophilia how do you treat
depending on the clinical picture-only offer anticoagulation if RECURRENT thrombotic events
why in hereditary throbophilias do you not always anticoagulate
many factors influence the patients risk of thrombosis beyond the genetic predisposition
name an acquired thrombophilia
antiphospholipid antibody syndrome
what carries a greater risk factor for thrombosis acquired or hereditary thrombophilia
acquired thrombophilia
what are the features of antiphospholipid syndrome
recurrent thrombosis-arterial including TIA and venous
recurrent fetal loss
mild thrombocytopenia
in terms of haemostasis what does antiphospholipid syndrome cause
conformational change in B2 glycoprotein which leads to activation of both primary and secondary haemostasis and vessel wall abnromalities
how is antiphospholipid syndrome treated
aspirin and warfarin
what does heparin do
potentiates antithrombin with immediate effect
what are the 2 forms of heparin
unfractioned and LMWH
how do you monitor heprain
for unfractioned APTT
for LMWH-anti Xa assay but usually no monitoring of LMWH is required as more predictable response
what are the complications of heparin
bleeding
heparin induced thrombocytopenia (wit thrombosis) HITT
because of the risk of HITT what do you monitor patients on heparin for
FBC
what is a long term complication of heparin
osteoporosis
describe the soluble properties of vit K
fat soluble vitamin
where is vitamin K absorbed
upper intestine
what does vitamin K require for absorbption
bile salts
what does vitamin K do
final carboxylation of clotting factors II, VII, IX and X
how should warfarin be taken
dose should be taken at same time every day
how is the INR calculated
patients PT in seconds divided by mean normal PT in seconds
give an example of a Xa inhibitor
Rivaroxaban
give an example of thrombin inhibitors
dabigatran
what is the most common hereditary blood-clotting disorder
won Willebrand disease
what is von Willebrand factor required for
platelet adhesion
how is von Willebrand disease most commonly inherited
autosomal dominant
what does von Willebrand usually present with
varying degrees of bleeding tendency usually from bruising, nosebleeds and bleeding gums
describe the blood results of someone with von Willebrand disease
usually get elevated PT. APTT may be prolonged, factor VIII decreased (vwF is bound to Factor VIII)
what role does von Willebrand factor have in blood clotting
endothelial (vessel wall) damage exposes collagen and releases von Willebrand factor and other proteins to which platelets have receptors-platelet adhesion at site of injury
what is the treatment of von Willebrand disease
transexamic acid for mild bleeding, desmopressin can also increase levels of vWF by inducing the release of vWF from endothelial cells
what type of disease is Factor V Leiden
most common inherited thrombophilia
how is Facor V Leiden inherited
either homozygous or heterozygous
after VTE do you screen for Factor V Leiden
isn’t recommended as previous thromboembolism itself is risk factor for further events and this should dictate specific management in the future rather than the thrombophilia identified
