heritable blood disorders Flashcards
what is haemostasis
balance between bleeding and clotting
what will a breech in vaso-integrity cause
vasoconstriction and activation platelets at injury then aggregation to form a plug
coagulation then activated = fibrin plug
during platelet activation what factors are released
thromboxane A2 - more platelet aggregation
vWF
fibrinogen
what platelets protein receptors are from vWF and fibrinogen
vWF - glycoprotein 1b9
fibrinogen - glycoprotein 2b3a
what happens when vWF and fibrinogen binds to platelet proteins receptors
vWF - acts as glue which allows platelets to adhere to collagen of epithelium
fibrinogen - allows platelets to stick to each other
how do these drugs affect platelet aggregation
clopidegral
aspirin
clopidegral stops platelet activation
aspirin stops CDX and thromboxane release
describe the extrinsic coagulation pathway
activated first
exposure of tissue factor activates VII, f VIIa activates X, Xa and Va activate prothrombin to produce thrombin from fibrinogen
describe the intrinsic pathway
when blood gets involved with foreign object
XII activated which actauvtes XI and IX then follows extrinsic
which factor is vital for fibrin
factor X
describe the process of fibrinolysis
plasmin breaks down cross linked fibrin into fibrin products
plasmin produced by tissue plasminogen activator
give 4 examples of how types bleeding disorders
congenital - single gene
acquired - multiple
platelet/vessel wall defect
coagulation defect
what do platelet /vessel wall defects lead to as well as coagulation defects
p/v - mucosal and skin bleeding (gums)
c - deep muscular bleeds
what investigations can be done for bleeding disorders
FBC
coagulation screen
clauss fibrinogen
vWF profile
how do you measure the intrinsic vs extrinsic pathway
in - APTT - activated partial thrombplastin time
ex - PT - prothrombin time
what do platelet/vessel wall defects leeds to
all give rise to prolonged bleeding time
scurvy (lack vit C)
vWD
what are the disease differences between vascular/platelt defects compared to coagulation defects
v/p - superficial bruises, spontaneous, bleeding from skin, immediate and prolonged bleeding
c - deep spreading haemotoma, haemarthrosis, bleeding prolonged
what are the three types of vWD
1 - reduced production of normal molecule - lack of vWF
2 - normal count of abnormal molecule
3 - absence of molecule - severe
what is the most common bleeding disorder
type 1 vWD
what i the inheritance pattern of the types of vWD
normal = AD inheritance
type 3 = AR
where is vWF stored and released
endothelial cells - secreted into plasma
what is the role of vWF
acts as a glue for platelet aggregation to vessel walls
and as a carrier for VIII
what is the presentation of vWD
defective primary homeostasis, skin and mucosal bleeding
what is the treatment of vWD
antifibrinolytics - tranexamic acid
DDAVP (desmopressin) - promotes release of vWF from storage granules
factor concentrates containing vWD
what is haemophilia and types
x linked recessive - most common clotting factor deficiencies
a - factor VIII deficiency
b - factor IX deficiency
what disease would you get bleeding into joint and what is the terminology
haemophilia haemarthrosis (joint bleeding)
what is the treatment of haemophilia
severe - replacement of missing clotting protein
mild to moderate - DDAVP (desmopressin) (doesn’t work for HB)
what are some complications of the treatment of haemophilia
transfusion transmitted infections
inhibitor development - factor doesn’t work
immune tolerance
