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Clinical Pathology > CP7-4 heritable bleeding disorders > Flashcards

CP7-4 heritable bleeding disorders Flashcards

1
Q

What is balanced in the hemostatic balance?

A

Bleeding and clotting

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2
Q

How are hemostatic plugs formed?

A

primary hemostasis of aggregation of platelets and secondary hemostasis of coagulation with thrombin and fibrin combines to form a clot

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3
Q

What does factor X become when it is activated (I.e. becomes factor Xa)?

A

A protease enzyme that cleaves factor II

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4
Q

Which clotting cascade is tissue factor involved in?

A

The extrinsic pathway

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5
Q

How does tissue factor contribute to the extrinsic clotting pathway?

A

Factor VII becomes activated and then activates factor X with calcium

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6
Q

When does factor XII become activated in the intrinsic pathway?

A

When it comes in contact with a foreign surface

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7
Q

What tests can be done to look at how quick clotting pathways work?

A

Prothrombin time - speed of extrinsic pathway
Activated partial thromboplastin time - speed of intrinsic pathway
Thrombin clotting time - adding thrombin to plasma and seeing how long a clot takes to form
Euglobulin lysis time

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8
Q

What are two procoagulant components?

A

Platelets
Clotting factors

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9
Q

What are 4 anti-coagulant components?

A

Protein C
Protein S
Anti+thrombin III
Fibrinolytic system

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10
Q

How many defects are usually caused by congenital bleeding disorders?

A

Usually 1

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11
Q

How many defects are usually caused by acquired bleeding disorders?

A

Usually multiple

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12
Q

What defect is usually caused by disorders affecting platelets/vessel wall?

A

Mucosal and skin bleeding

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13
Q

What can coagulation defects cause?

A

Deep muscular and joint bleeds and bleeding following trauma

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14
Q

What investigations can be done into potential bleeding dirsorders?

A

FBC and blood film
Coagulation screen and Clauss fibrinogen screen
D-dimer if suspicious of acquired disorder
Von Willebrand profile
Coagulation factor assays including FVIII and FIX
Inhibitor assays
Platelet function tests

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15
Q

What are further non-routine investigations into bleeding disorders if other tests are normal but suspicion remains?

A

FXIII assay
Assay of alpha2antiplasmin

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16
Q

What are examples of bleeding disorders?

A

Thrombocytopenia
Disorders of platelet function
Von Willibrand disease
Factor XIII deficiency
Mild coagulation factor deficiency
Vascular disorders
(Rarely) disorder of fibrinolysis

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17
Q

What are some defects that can lead to prolonged bleeding times?

A

Reduced number of platelets
Abnormal platelet function
Abnormal vessel wall
Abnormal interaction between platelets and vessel wall

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18
Q

What are petechiae rashes?

A

Rashes as a result of bleeding into the skin which do no blanch with pressure and are non palpable

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19
Q

What is the most common mild bleeding disorder?

A

Von willibrand disease

20
Q

What is the function of Von Willebrand factor?

A

Helps platelets stick to the vessel wall by interacting with collagen in the wall

21
Q

Type 1 and most type 2 Von Willebrand disease is inherited through which inheritance pattern?

A

Autosomal dominant

22
Q

Type 3 Von Willebrand disease is inherited through what inheritance pattern?

A

Autosomal recessive

23
Q

What clotting factor is Von Willebrand factor part of?

A

Factor VIII

24
Q

What care complications of VWD?

A

Defective haemostasis
Variable reduction in VIII levels
Mucocutaneous bleeding including menorrhagia in women
Increased postoperative and postpartum bleeding

25
Q

Who is more symptomatic with VWD? Men or women?

A

Women - both affects by VWD but women usually have more symptoms

26
Q

What are confounding factors which affect diagnosis of mild VWD?

A

Contraceptive pill
Increased exercise
Psychological stress

27
Q

Which blood group has lower vWF levels?

A

Group O

28
Q

How is VWD treated?

A

With antifibrinolytics like tranexamic acid
With DDAVP if type 1
With factor concentrates containing vWF (either derived from plasma or recombinant)
Vaccination against hepatitis
In women combined oral contractile pill or inuterine system to increase progesterone hormones for menorrhagia

29
Q

What clotting factors have hereditary deficiencies? How common are each?

A

XII - relatively common
XI - rare
IX haemophilia B - uncommon
VIII haemophilia A - uncommon
VIII vWD- common
VII, X, V, II, I & XIII - very rare

30
Q

Why is factor XII deficiency common but not usually a problem?

A

Deficiency of factor XII doesn’t usually cause clinical bleeding problems

31
Q

What factor deficiencies are inherited autosomally?

A

XII
XI

32
Q

What factor deficiencies are inherited in a sex linked recessive inheritance pattern?

A

IX and VIII haemophilia A&B respectively

33
Q

Who is more likely to be affected by haemophilia?

A

Men as women have two X chromosomes which acts as a protective factor although they are still carriers

34
Q

What is the epidemiology in men of haemophilia A and B?

A

A = 1 in 5000
B = 1 in 30,000

35
Q

What factor deficiency/defect is inherited autosomal dominantly?

A

vWD - factor VIII

36
Q

What factor deficiencies/defects are inherited in an autosomal recessive inheritance pattern?

A

I, II, V, VII, X, XIII

37
Q

What is the pattern of severity between family members?

A

Severity is consistent

38
Q

What percentage of haemophilia cases are due to de novo mutations?

A

Around 30%

39
Q

What percentage of factor VIII or IX, compared to normal levels, are found in each severity of haemophilia? (Mild/moderate/severe)

A

Mild = 6-50% of normal
Moderate = 1-5% of normal
Severe = <1% of normal

40
Q

What are symptoms of mild haemophilia?

A

Won’t usually have spontaneous bleeds but will have increased bleeding after surgery or trauma

41
Q

What type of bleeds occur in people with haemophilia?

A

Spontaneous bleeds
Post traumatic bleeds
Joint bleeding aka haemarthrosis
Muscle haemorrhage
Soft tissue bleeding
Life threatening bleeding

42
Q

How is haemophilia treated/managed?

A

Replacement of missing clotting protein either in demand or by prophylaxis
DDAVP if mild/moderate haemophilia A
Factor concentrates (usually recombinant)
Anti fibrinolytic agents
Vaccination for hepatitis A and B

43
Q

What are some transfusion transmitted infections that can complicate haemophilia?

A

Hepatitis A, B and C (and G)
HIV
Parvovirus
vCJD

44
Q

How does inhibitor development complicate treatment of haemophilia?

A

Shortens half life of factor replacement therapy leading to poorer clinical response and poor recovery

45
Q

How is inhibitor development in haemophilia treated/prevented?

A

With specialised management of bleeds
Emicizumab prophylaxis
Eradication of inhibitor e.g with immune tolerance

46
Q

What is emicizumab?

A

A SC injected humanised bispecific monoclonal antibody which bridges FIXa and FX to restore function of missing FVIIIa and is not expected to be affected by or induce inhibitors/inhibition to help treat haemophilia A

47
Q

What are some new haemophilia treatments being developed?

A

Gene therapy
EHL products
AntiTFPI antibodies
AT mRNAi

Clinical Pathology (65 decks)

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