8 - Abnormalities of Haemeostasis

Question 1

What is meant by epistaxis?

Answer 1

nosebleeds

Question 2

Broadly speaking, what are the two causes of abnormal haemostasis?

Answer 2

Lack of a specific factor

Defective function of a specific factor

Question 3

What can cause thrombocytopenia?

Answer 3

Failure of production – bone marrow failure e.g. leukaemia, B12 deficiency
Accelerated clearance e.g. autoimmune thrombocytopenia, DIC

Question 4

State one very common cause of thrombocytopenia.

Answer 4

Autoimmune thrombocytopenia

Question 5

What is a distinctive clinical feature of thrombocytopenia?

Answer 5

Petechiae

Question 6

Broadly speaking, state three causes of thrombocytopenia.

Answer 6

• Failure of platelet production by the megakaryocytes
• Shortened half-life of platelets
• Increased pooling of platelets in an enlarged spleen (hypersplenism)

Question 7

State three hereditary platelet defects.

Answer 7

Glanzmann’s Thrombasthenia – absence of GlpIIb/IIIa (prevents platelet aggregation)
Bernard Soulier Syndrome – absence of GlpIb (prevents binding to von Willebrand factor)
Storage Pool Disease – storage granules are not able to release adequately

Question 8

State a broad acquired cause of impaired platelet function.

Answer 8

Drugs e.g. NSAIDs, clopidogrel

Question 9

What are the two roles of von Willebrand factor in haemostasis?

Answer 9

Binding to collagen and trapping platelets

Stabilising factor 8 (if VWF is low, factor 8 may be low)

Question 10

Von Willebrand Disease is usually hereditary. What are the three types of von Willebrand disease? State their pattern of inheritance.

Answer 10

Type 1 – deficiency of VWF but it functions normally (autosomal dominant)
Type 2 – VWF does not function normally (autosomal dominant)
Type 3 – VWF not made at all (autosomal recessive)

Question 11

State two inherited vessel wall conditions that cause defects in primary haemostasis.

Answer 11

Hereditary haemorrhagic telangiectasia

Ehlers-Danlos Syndrome

Question 12

State some acquired causes of vessel wall conditions that cause defects in primary haemostasis.

Answer 12

Scurvy
Steroid therapy
Ageing (senile purpura)
Vasculitis

Question 13

Describe the pattern of bleeding in defects of primary haemostasis.

Answer 13

The primary platelet plug isn’t strong enough to stop the bleeding 
Bleeding is immediate
Prolonged from cuts 
Epistaxes 
Gum bleeding 
Menorrhagia 
Easy bruising 
Prolonged bleeding after trauma and surgery

Question 14

How are the clotting factors affected in severe von Willebrand disease?

Answer 14

Reduced factor 8 (because VWF stabilizes factor 8)

This causes haemophilia type bleeding patterns

Question 15

What tests can be done for disorders of primary haemostasis?

Answer 15

Platelet count
Bleeding time
Assays for VWF
Clinical observation

Question 16

What is haemophilia caused by? What is its pattern of inheritance?

Answer 16

Lack of Factor 8 (A) or Factor 9 (B)
This leads to impaired thrombin generation
In haemophilia you get failure to generate fibrin to stabilize the platelet plug
It is X-linked recessive

Question 17

Describe the difference in outcome for deficiencies of factors 2, 8 & 9, 11 and 12.

Answer 17

2 – lethal
8 & 9 (haemophilia) – severe but compatible with life
11 – bleeding after trauma but not spontaneously
12 – no excess bleeding

Question 18

State some acquired causes of deficiency of coagulation factors.

Answer 18

Liver disease
Dilution
Anti-coagulant drugs (e.g. warfarin)

Question 19

State some disorders of coagulation that are due to increased consumption.

Answer 19

Disseminated intravascular coagulation (DIC)

Autoimmune thrombocytopenia

Question 20

What happens in Disseminated Intravascular Coagulation (DIC)?

Answer 20

Generalised activation of coagulation
It is associated with sepsis, inflammation and tissue necrosis
It consumes and depletes coagulation factors
Platelets are consumed

Question 21

Describe the pattern of bleeding in coagulation disorders.

Answer 21

Superficial cuts DO NOT bleed (because primary haemostasis is fine)
Bruising is common
Spontaneous bleeding is DEEP, into muscles and joints
Bleeding after trauma may be delayed and prolonged
Frequently restarts after stopping

Question 22

What is the hallmark of haemophilia?

Answer 22

Haemarthrosis

Question 23

What simple medical procedure must you avoid doing to patients with haemophilia?

Answer 23

Intramuscular injection – it can cause deep bleeding patterns

Question 24

State some tests that are used for coagulation disorders.

Answer 24

Screening Tests – APTT, PT & Platelet Count
Factor Assays
Tests for inhibitors

Question 25

Describe the APTT and PT results for a patient with haemophilia.

Answer 25

Prolongs APTT but normal PT

This is because the defect lies in the intrinsic pathway (factor 8 or 9)

Question 26

State some bleeding disorders that are not detected by routine clotting tests.

Answer 26

Mild factor deficiencies 
Von Willebrand Disease 
Factor 8 Deficiency (cross-linking)
Platelet disorders 
Excessive fibrinolysis 
Vessel wall disorders 
Metabolic disorders (e.g. uraemia) 
NOTE: urea interferes with platelet function

Question 27

State a hereditary disorder of fibrinolysis.

Answer 27

Antiplasmin deficiency

Question 28

State two acquired disorders of fibrinolysis.

Answer 28

Drugs such as tissue plasminogen activator

Disseminated intravascular coagulation (DIC) – because everything has been used up

Question 29

What is the treatment that is considered for a patient whose abnormal haemostasis is caused by immune destruction of platelets?

Answer 29

Immunosuppression (e.g. prednisolone)

Question 30

What clotting factors are found in cryoprecipitate?

Answer 30

Fibrinogen
Factor VIII
Factor XIII
Von Willebrand Factor

Question 31

Factor concentrates are available for all factors except which one?

Answer 31

Factor V

Question 32

Describe the use of Desmopressin (DDAVP) in von Willebrand disease.

Answer 32

Desmopressin makes the endothelial cells release their stored VWF
This is good for people with mild von Willebrand disease (as it releases endogenous stored of VWF)

Question 33

State two other drugs that are used as haemostatic treatments.

Answer 33

Tranexemic acid (inhibits fibrinolysis)
Fibrin glue