9. Disorders of Haemostasis Flashcards

1
Q

4 things causing defective haemostasis

A
  1. abnormalities in vasc system
  2. thrombocytopenia
  3. thrombocytopathy (disordered platelet function)
  4. defective coagulation
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2
Q

what is most sever disorder

A

coagulation disorder
bleeding can be into joints and soft tissues

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3
Q

characteristics of vascular bleeding disorders

A
  • easy bruising
  • spontaneous bleeding from small vessels
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4
Q

main type of inherited vascular disorder

A

hereditary harmorrhagic telangiectasia (HHT)

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5
Q

what type of genetic defect is HHT

A

autosomal dominant
so effects men and women equally

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6
Q

what happens in people with HHT

A

arterovenous malformations
(connection between arteries and veins will bypass the capillaries)

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7
Q

symptoms of HHT

A
  • telangiectases on nose, tongue, lips = vry common)
  • nosebleeds
  • GI blood loss (bit more rare) = can lead to chronic iron deficiency
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8
Q

when and what treatment used for HHT

A

if small blood loss, then no intervention needed
otherwise:
- embolisation = introducing artificial blood clot
- laser treatment to fuse vessels
- tranexamic acid

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9
Q

3 types of vascular purpura

A
  • purpura simplex
  • senile purpura
  • infection associated purpura
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10
Q

when can infection associated purpura be lethal

A

whne in unvaccinated individuals
viruses like measles can damage blood vessels around brain or organs

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11
Q

thrombocytopenia meaning

A

deficiency in plateley numbers
lower than 150x10^9/L

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12
Q

3 main causes of thrombocytopenia

A
  • failure of platelet production (most common)
  • increased destruction of platelets
  • sequesteration of platelets
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13
Q

what might cause failure on platelet productio

A

usually bone marrow failure
- aplastic anaemia
or
- leukemia
(2 things that can cause the bone marrow failure)

  • drug/viral toxicity
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14
Q

How can we diagnose thrombocytopenia

A
  • clinical history
  • peripheral blood count
  • blood film
  • bone marrow exam
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15
Q

main cause of increased destruction of platelets

A

autoantibodies attaching to platelet surface
(so some kind of autoimmune disease)

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16
Q

main type of autimmune disease causing destruction of platelets

A

Idiopathic thrombocytopenia purpura (ITP)
can be CHRONIC or ACUTE

17
Q

people who usually get chronic ITP

A

women 15-50yrs old

18
Q

what type of antibodies attach onto platelets in chronic ITP

A

IgG
acts against glycoprotein IIb/IIIa or Ib

19
Q

who does acute ITP usually affect

A

children under 10

20
Q

what might trigger acute ITP

A

abrupt onset after vaccination
or viral infection e.g. after chicken pox, measles

21
Q

how might post viral cause acute ITP

A

IgG antibody can attach to viral antigen thats absorbed onto the platelet surface

22
Q

consequences of acute ITP

A

usually spontatneous remission
minority of cases will develop chronic ITP

23
Q

name of disease that causes sequestration of platelets

A

splenomegaly

24
Q

what can splenomegaly cause

A

goes from usual 30% in spleen up to 90%
= leads to thrombocytopenia

25
Q

what might splenomegaly be caused by

A

leukemia
- over production of cells
- ends up in spleen
= leads to enlarged, palpable spleen

26
Q

what is thrombocytopathy

A

disorder of plateley function
(will have NORMAL platelet count)

27
Q

what 2 types of thrombocytopathy disorders are there

A

inherited and acquired
(inherited much more rare)

28
Q

2 ways thrombocytopathy can be acquired

A
  • antiplatelet drugs
  • haematological malignancy
29
Q

what drug may cause thrombocytopathy

A

aspirin

30
Q

how can spirin inhibit platelet aggregation

A
  • irreversibly inactivates cyclooxygenase (COX)
  • which usuallly oxygenates arachindonic acid to thromboxane A2
31
Q

what do we need to check for before aspirin

A

obvs other stuff too
but need to make sure they dont already have a low platelet count

32
Q

what 2 types of haematological malignancy can affect platelet function

A
  • acute myeloid leukemia
  • any myeloproliferative disorders and myeloma
33
Q

diagnosing platelet disorders

A
  • clinical history
  • initial blood count and blood film exam
  • bone marrow biopsy
  • bleeding time
34
Q

what might a bone marrow biopsy be used for

A

thrombocytopenic patients
detect malignancy (failure of platelt production)

35
Q

if blood count is in normal limits then what might be done

A

tests to detect abnormal platelety function

36
Q
A