Bleeding disorders Flashcards
What are the four main types of bleeding disorder?
Von Willebrand disease
Haemophilia A
Haemophilia B
Disseminated intravascular coagulation
What is Von Willebrand factor?
A glycoprotein found in blood plasma that plays a role in platelet adhesion
What can Von Willebrand bind to?
Subendothelial collagen
GP IIb / IIIa
What clotting factor is Von Willebrand bound to when inactive in circulation?
Factor VIII
What protein activates VWF to release from Factor VIII and bind to other platelet receptors?
Thrombin
How may patients with a bleeding disorder present?
Which type of VWD does a patient have a complete absence of VWF?
Type 3
(there’s only three types, 3 is most severe)
What drug can be given to patients with VWD in preparation for trauma or surgery?
Desmopressin - stimulates the release of VWF from endothelial cells.
What percentage of people have clinically significant VWD?
0.01%
What causes haemophilia A?
Deficiency in factor VIII
What causes haemophilia B?
Deficiency in factor IX
What type of inheritance are haemophilia A and B?
X-linked recessive (therefore almost exclusively affects males)
When do most cases of haemophilia present?
As neonates or in early childhood
Spontaneous bleeding into which parts of the bodies is a classic feature of haemophilia?
muscles and joints (haemoarthrosis)
How can acute episodes of bleeding be managed in haemophilia?
Infusions of either Factor VIII or IX
Desmopressin to stimulate VWF release
Antifibrinolytics e.g tranexamic acid
How do fibrinolytics work?
Stop fibrinolysis (breakdown of clots)
What is disseminated intravascular coagulation (DIC)?
a condition in which there is a simultaneous tendency to spontaneous bleeding and thrombosis.
What do you paradoxically simultaneously see in disseminated intravascular coagulation (DIC)?
Simultaneously have clotting and spontaneous bleeding!
- coagulation cascades being activated in vessels around the body leading to microvascular thrombosis.
- this means circulating platelets + coagulation factors are lowered as they’ve being consumed by the thrombi - thrombocytopenia.
Acute DIC can be caused by what?
Chronic DIC can be caused by what?
Acute - sepsis, trauma, haemolytic transfusion reactions
Chronic - cancer
(+ other infectious vs non-infectious causes!)
What does the D-dimer test test for?
Levels of D-dimer protein (produced in the breakdown of fibrin clots)
What does a high level of D-dimer protein indicate?
That you have a clotting disorder of some sort as significant clot breakdown is going on.
What enzyme breaks down clots?
Plasmin
Give two complications of disseminated intravascular coagulation (DIC).
multi-organ failure
haemorrhage
