PBL 2: Sharon Phillips Flashcards
What are the routine coagulation tests?
- prothrombin time assess extrinsic pathways
- activated partial prothrombin time assess intrinsic pathways
- bleeding time assess platelet function
How is the bleeding test done?
Scalpel blade is used to make a shallow incision on underside of forearm superficially
Time measured from when incision made and bleeding stopped
Should be 3-10 minutes for normal adult
What is INR?
Compensates for different manufactures giving slightly different results
Derived from Prothrombin Time
Standard Value
Should be 0.8-1.2
How do you test Prothrombin Time?
Mix tissue factor (3) and calcium with delcalcified, platelet poor plasma
How do you test activated partial prothrombin time?
Addition of contact activator (kaolin) and phospholipids
How do you test thrombin time?
Test for deficiency in fibrinogen/thrombin inhibition
Add thrombin to platelet poor plasma and measure to time taken for blood clot to form
What suggests that she has Von Willebrand’s disease?
Factor VIII levels are low so haemophilia A or VWD
Factor IX levels normal so not Haemophilia B
Prolonged bleeding time
Low VWF factor so VWD
What is the function of VWF?
Forms bridge between collagen and platelet in platelet adherence to form a platelet plug
Why is factor VIII low?
Factor 8 bound to VWF and VWF prevents it from proteolysing
What are the types of VWD
- type 1: VWF production reduced, most common, mild to moderate
- type 2: protein present but reduced/defective
- type 3: total absent protein
What are the symptoms of VWD?
Excessive bleeding Bruising Frequent nosebleeds Menorrhagia Heavy menstruation OR asymptomatic, only notice when have an injury
What is the treatment for VWD?
Not always necessary
Prior to surgery/dental work intravenous desmopressin acetate to increase VWF levels stimulating coagulation (nasal inhaler for mild cases)
Intravenous factor VIII which is rich in VWF
What should VWD sufferers avoid?
Avoid damage to liver as cirrhosis interferes with its ability to produce proteins and coagulation factors - alcohol intake, binge drinking avoid
What is the inheritance of VWD compared to haemophilia?
Autosomal dominant - VWD (individual is female and mother also affected not likely to be X linked not haemophilia)
Haemophillia ix X linked
What can desmopressin cause?
Hyponatremia
