9. Disorders of Haemostasis

Question 1

4 things causing defective haemostasis

Answer 1

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

Question 2

what is most sever disorder

Answer 2

coagulation disorder
bleeding can be into joints and soft tissues

Question 3

characteristics of vascular bleeding disorders

Answer 3

• easy bruising
• spontaneous bleeding from small vessels

Question 4

main type of inherited vascular disorder

Answer 4

hereditary harmorrhagic telangiectasia (HHT)

Question 5

what type of genetic defect is HHT

Answer 5

autosomal dominant
so effects men and women equally

Question 6

what happens in people with HHT

Answer 6

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

Question 7

symptoms of HHT

Answer 7

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

Question 8

when and what treatment used for HHT

Answer 8

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

Question 9

3 types of vascular purpura

Answer 9

• purpura simplex
• senile purpura
• infection associated purpura

Question 10

when can infection associated purpura be lethal

Answer 10

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

Question 11

thrombocytopenia meaning

Answer 11

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

Question 12

3 main causes of thrombocytopenia

Answer 12

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

Question 13

what might cause failure on platelet productio

Answer 13

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

• drug/viral toxicity

Question 14

How can we diagnose thrombocytopenia

Answer 14

• clinical history
• peripheral blood count
• blood film
• bone marrow exam

Question 15

main cause of increased destruction of platelets

Answer 15

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

Question 16

main type of autimmune disease causing destruction of platelets

Answer 16

Idiopathic thrombocytopenia purpura (ITP)
can be CHRONIC or ACUTE

Question 17

people who usually get chronic ITP

Answer 17

women 15-50yrs old

Question 18

what type of antibodies attach onto platelets in chronic ITP

Answer 18

IgG
acts against glycoprotein IIb/IIIa or Ib

Question 19

who does acute ITP usually affect

Answer 19

children under 10

Question 20

what might trigger acute ITP

Answer 20

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

Question 21

how might post viral cause acute ITP

Answer 21

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

Question 22

consequences of acute ITP

Answer 22

usually spontatneous remission
minority of cases will develop chronic ITP

Question 23

name of disease that causes sequestration of platelets

Answer 23

splenomegaly

Question 24

what can splenomegaly cause

Answer 24

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

Question 25

what might splenomegaly be caused by

Answer 25

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

Question 26

what is thrombocytopathy

Answer 26

disorder of plateley function (will have NORMAL platelet count)

Question 27

what 2 types of thrombocytopathy disorders are there

Answer 27

inherited and acquired (inherited much more rare)

Question 28

2 ways thrombocytopathy can be acquired

Answer 28

- antiplatelet drugs - haematological malignancy

Question 29

what drug may cause thrombocytopathy

Answer 29

aspirin

Question 30

how can spirin inhibit platelet aggregation

Answer 30

- irreversibly inactivates cyclooxygenase (COX) - which usuallly oxygenates arachindonic acid to thromboxane A2

Question 31

what do we need to check for before aspirin

Answer 31

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

Question 32

what 2 types of haematological malignancy can affect platelet function

Answer 32

- acute myeloid leukemia - any myeloproliferative disorders and myeloma

Question 33

diagnosing platelet disorders

Answer 33

- clinical history - initial blood count and blood film exam - bone marrow biopsy - bleeding time

Question 34

what might a bone marrow biopsy be used for

Answer 34

thrombocytopenic patients detect malignancy (failure of platelt production)

Question 35

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

Answer 35

tests to detect abnormal platelety function