Week 3- bleeding disorders Flashcards

1
Q

What are some causes of vascular abnormalities that could lead to a disorder of primary haemostasis?

A

Marfans syndrome- collagen is affected so they get excessive bruising, bleeding and floppy heart valves

Vasculitis- inflammation- usually autoantibodies attack vessels making them leaky

Old age- you lose collagen as you grow older.

Steroids- Can lead to thinning of the skin and vessel wall injury by reducing collagen.

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2
Q

Someone suffering from henloch schonlein purpura will have what symptoms?

A

They will have mucosal and GI bleeds.

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3
Q

What does thrombocytopenia mean?

A

Low platelets.

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4
Q

Is thrombocytopenia a hereditary or acquired disease?

A

Hereditary thrombocytopenia Is extremely rare.

Acquired is much more common.

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5
Q

What are the two broad reasons for acquired thrombocytopenia?

A

Reduced production-bone marrow problem

Increased destruction

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6
Q

What are the causes of peripheral platelet destruction?

A

Coagulopathy- e.g. DIC
Autoimmune- immune thrombocytopenic purpura (ITP)
Hypersplenism- anything that causes the spleen to be enlarged e.g. portal hypertension.

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7
Q

Describe what occurs in ITP?

A

Autoantibodies stick to the platelets and cause them to be removed by the reticuloendothelial system.
The bone marrow makes lots and lots of platelets but they are killed, leaving the patient thrombocytopenic.

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8
Q

What can cause functional defects in platelets?

A

Drugs e.g. aspirin, NSAIDs. Stop the platelets sticking together.
Renal failure- a build up of toxins can interfere with platelet function.

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9
Q

Is VWF deficiency hereditary or acquired?

A

Hereditary is much more common than acquired.

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10
Q

How is VWF deficiency inherited?

Who does it affect?

A

Autosomal dominantly.

Affects both men and women equally, however tends to be seen more in women because of heavy periods.

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11
Q

What type of haemostasis does VWF deficiency affect?

A

Mainly primary however also affects secondary. VWF carries around factor VIII so without it you will also have a factor VIII deficiency.

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12
Q

What symptoms will be seen with VWF deficiency?

A

Mucosal bleeding
Purpura (bruising)
Menorrhagia in women.

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13
Q

What can failure of the fibrin clot forming be due to?

A

Single clotting factor deficiency
Or
Multiple clotting factor deficiencies.

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14
Q

What are some causes of single clotting factor deficiencies?

A

Generally hereditary causes e.g. haemophilia.

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15
Q

What are some causes of multiple clotting factor deficiencies?

A

These are generally acquired e.g.
DIC
Liver failure- all the clotting factors are produced here so without this you can’t make them
Vitamin K deficiency/warfarin therapy- to get the negative charge on the clotting factors to be attracted to the platelets, you need vitamin K.

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16
Q

What investigations are done into vitamin K deficiency and what are their results?

A

Do APTT and PT.
Both will be prolonged as the clotting factors are not attracted to the platelet plug. Tends to be more sensitive to factor VII so PT may be prolonged more.

17
Q

Where are coagulation factors synthesised?

A

In liver hepatocytes.

18
Q

Which factors are carboxylated by vitamin K?

A

10, 9, 7, 2.

19
Q

How does vitamin K get into the body?

A

Brought in by our diet and also synthesised by the intestine.

20
Q

Where is vitamin K absorbed?

A

Absorbed in the upper intestine.

21
Q

What is needed for vitamin K absorption?

A

Bile salts (therefore gall bladder has to be working properly).

22
Q

What are some causes of vitamin K deficiency?

A

Poor dietary intake (present in leafy green veg).
Malabsorption
Obstructive jaundice- Bile salts are not getting into the bowel.
Vitamin K antagonists (warfarin)
Haemorrhagic disease of the newborn- lack of vitamin K at birth.

23
Q

What is disseminated intravascular coagulation?

A

Excessive and inappropriate activation of the haemostatic system.
You get microvascular thrombus formation, which can lead to end organ failure.
Also clotting factor consumption leading to bruising, purpura and generalised bleeding.

24
Q

Which test is likely to show failure of multiple clotting factors first?

A

Likely to be prothrombin time as this one contains factor VII. Factor VII has a half life of about 7 hours whereas the others have a half life of about 3 days.

25
Q

How can you distinguish between DIC and liver failure causing the multiple clotting factor deficiencies?

A

In DIC- the D dimers will be greatly increased as massive fibrinolysis is occurring. Whereas in liver failure they may be raised but not a lot.

26
Q

What can cause DIC?

A

Sepsis
Obstetric emergencies (placenta is very rich in tissue factor so if it infarcts, massive amounts of this are released into the mothers circulation)
Malignancy
Hypovolaemic shock- lack of oxygen leading to mass tissue damage.

27
Q

How do you treat DIC?

A

Treat the underlying cause
Replacement therapy- replace platelets, replace fibrinogen (cryoprecipitate), plasma transfusions (this will only maintain their state, you need to treat the underlying cause for them to become better).

28
Q

What is haemophilia?

A

An X linked hereditary disorder in which abnormally prolonged bleeding recurs episodically at one or a few sites on each occasion.

29
Q

What is haemophilia A?

A

A factor VIII clotting deficiency.

30
Q

What is haemophilia B?

A

A factor IX clotting deficiency.

31
Q

Which is the more common haemophillia?

A

Factor VIII (A) is far more common than haemophilia B.

32
Q

Will people with haemophilia suffer with nose bleeds, paper cuts bleeding excessively?

A

No- there is no issue with primary haemostasis. You will only get bleeding from medium-large blood vessels.

33
Q

What will be shown in PT and APTT tests with haemophilia?

A

PT will be normal

However they will have a prolonged APTT.

34
Q

What are the clinical features of haemophilia A and B?

A
Recurrent haemarthroses (bleeding into joints and muscles)
Recurrent soft tissue bleeds
Prolonged bleeding after surgery, dental extractions and invasive procedures.
35
Q

Which joints tend to be bled into in haemophilia?

A

Ankle, knee, elbow (weight bearing joints)

36
Q

What occurs in the joint once there has been a bleed?

A

The bleeding irritates the synovium, leading to formation of new blood vessels (neovascularisation). This blood vessels formed are leaky and more prone to bleeding.
After recurrent bleeding you get fusion of joints.

37
Q

In children, what treatment can be offered for haemophilia?

A

Factor VIII replacement.