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IMED2002 UWA > Disorders of Haemostasis > Flashcards

Disorders of Haemostasis Flashcards

1
Q

What causes bleeding?

A

Abnormalities of vasculature (could be due to connective tissue disorders or structural disorders)

Defects of primary haemostasis (platelet disorders)

Defects of secondary haemostasis (procoagulant protein deficiency)

Accelerated breakdown of clot (aka hyperfibrinolysis)

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2
Q

What does it mean to say quantitatiive defects of hamoestasis?

A

Not enough platelelets produced to produce platelet plug

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3
Q

What are some possible abnormalities in haemostasis?

A

Quantitative (not enough platelets to form platelet plug)

Qualitative defects

Both

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4
Q

What is the normal concentration of platelets in the blood?

A

150 - 400 x 10^9/L

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5
Q

When do issues arise with low platelet count?

A

20 - 50 x 10^9/L (bruising and surgical bleeding)

10 - 20 x 10^9 (nosebleeds and petechial rash)

<10 x 10^9/L (spontaneous serious bleeding)

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6
Q

What should be noted regarding platelet count?

A

Some people could be taking anti-platelet drugs due to their excessive coagulation ability.

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7
Q

What causes thrombocytopenia?

A

Congenital (inherited)

Acquired (impaired production at the bone marrow, hypersplenism, increased platelet destruction, and drug-induced)

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8
Q

What conditions can cause impaired bone marrow production of thromboyctes?

A

Myelodysplasia

Leukemia

Bone Marrow infiltration

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9
Q

What can cause increased platelet destruction?

A

Severe sepsis/DIC

TTP/HUS syndrome (fragmentation of blood cells and thrombocytes)

Immune thrombocytopenic purpura

Autoimmune conditions

Viral infections (HIV, hepatitis, H.pylori)

Pre-eclampsia

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10
Q

What drugs can reduce platelet count?

A

Heparin

Gold

Quinine

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11
Q

What is hypersplenism and how does it cause low platelet count?

A

Larger spleen resulting in more storage of thrombocytes at the spleen

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12
Q

What must be ensured with isolated thrombocytopenia conditions?

A

That the low platelet count is not caused by something else

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13
Q

What causes immune (idiopathic) thrombocytopenic purpura?

A

It is spontaneous and results in increased platelet destruction due to B cells producing IgG antibodies targeting the megakaryocytes

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14
Q

What do the IgG antibodies do to platelet production at the bone marrow?

A

They cause it to be stopped

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15
Q

How does immune thrombocytopenic purpura (ITP) present itself?

A

Children present with severe thrombocytopenia a few weeks after viral infection.

Adults present with more gradual onset and recovery. They can be treated with steroids, intravenous immunoglobulins, splenectomy, etc

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16
Q

What can activated GPIIb/IIIa bind?

A

fibrinogen

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17
Q

How can NSAIDs or other drugs like aspirin cause disorders in haemostasis?

A

They can reduce the action of cyclooxygenase which results in TXA2 deficiency and in turn inhibits platelet aggregation response

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18
Q

Name some inherited bleeding disorders:

A

Von-Willebrand’s disease

Haemophilia

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19
Q

Name some acquired bleeding disorders:

A

Liver disease

Vitamin K deficiency

Renal disease

Warfarin

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20
Q

What factors are deficient in haemophilia?

A

factor 8 and factor 9

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21
Q

When and how is haemmophilia typically diagnosed?

A

As infants diagnosed with severe bleeding under the skin.

Spontaneous haemarthrosis (bleeding into joints), muscle haematomas (due to bleeding into muscles), intracranial haemorrhage and internal bleeding

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22
Q

What is haemophilia A caused by?

A

Factor 8 (FVIII) deficiency

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23
Q

What is haemophilia B caused by?

A

Factor 9 (FIX) deficiency

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24
Q

What is another name for haemophilia B?

A

Christmas disease

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25
Q

Is bleeding in haemophilia A and B the same?

A

Yes, very similar

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26
Q

What kind of genetic inheritance does haemophilia follow?

A

X-linked recessive making it more likely in males

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27
Q

How is haemophilia diagnosed?

A

Most important clinical test is clinical history (i.e personal bleeding history, family history, and drugs)

Lab screening test (APTT would be extra long in haemophilia patients because factor 8 and 9 are in the intrinsic pathway)

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28
Q

An 18 month old boy with a short history of a painful swollen left knee. His blood was found to have a normal prothrombin time (PT) but an abnormally long APTT (93 seconds) and his factor VIII levels were <1% what is the diagnosis?

A

Haemophilia A

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29
Q

How is haemophilia managed?

A

Recombinant FVIII for procedures or treatment of bleeds. This is administered prior to procedures which can cause bleeding and as prophylaxis for newly diagnosed childred.

In the past they used blood donors to get FVIII which resulted in many people acquiring HIV and HepC.

In Australia all patients given the recombinant treatment.

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30
Q

What do patients with haemophilia have which details their diagnosis?

A

A haemophiliac card

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31
Q

What are the common differences between platelet defects and clotting factor deficiencies?

A

In platelet defects:
There is excessive bleeding after minor cuts which is not usual in clotting factor deficiencies

Petechiae are common (very uncommon in clotting factor deficiencies)

Ecchymoses are small and superficial in platelet defects and may be large and in soft tissues in clotting factor deficiencies

Haemarthroses are uncommon in platelet defects and common in clotting factor deficiencies

Bleeding with invasive procedures is immediate in platelet deficiencies and is delayed in clotting factor defects

Platelet conditions cause mucocutaneous bleeding whereas clotting factor deficiencies cause deep tissue bleeding

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32
Q

Do people with platelet defects bleed severely after minor cuts?

A

Yes

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33
Q

Do people with clotting factor deficiencies bleed severely after minor cuts?

A

Not usual

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34
Q

Which patients have petechiae typically; platelet defect patients or clotting factor deficient patients?

A

Platelet defect patients

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35
Q

Which factor is a carrying factor of factor 8?

A

Von-Willebrand factor

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36
Q

How is Von-Willebrand’s disease inherited?

A

Autosomal dominant condition found in 1% of the population

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37
Q

What are the types of VWD?

A

Type 1 (decreased quantity of VWF)

Type 2 (Decreased function of VWF)

Type 3 (rare, severe deficiency of VWF due to inheriting 2 mutated genes 1 from each parent)

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38
Q

How is VWD diagnosed in the lab?

A

May or may not have prolonged APTT (VWF carrier protein for FVIII)

von-willebrand screen can be done (VWF antigen level and VWF function tests such as collagen binding ability)

Factor VIII levels

Normal >50%, abnormal <30% and people with 30-50% are not diagnosed in this category but clinical history moves them one way or another.

39
Q

How is VWD treated?

A

DDAVP which causes release of VWF from storage granules in platelets and endothelium.

Tranexamic acid tablets (or mouthwash) which stabilizes fibrin clot which may be taken for first 4 - 5 days after the procedure.

Biostate which is taken for severe deficiency (Type 3 VWD) or in people who don’t respond to DDAVP. Plasma-derived product comes from blood donors that contains FVIII and VWF. It must be given on the same day as the procedure.

40
Q

What is DDAVP?

A

Desmopressin is a drug which is infused IV which increases VWF release from storage granules in platelets and endothelium.

It has a duration of effect of 4 - 6 hours so it must be given on the same day as procedure.

41
Q

What is Tranexemic acid?

A

Stabilizes fibrin clot which may be taken for first 4 - 5 days after the procedure.

42
Q

What is biostate? How is it made?

A

taken for severe deficiency (Type 3 VWD) or in people who don’t respond to DDAVP.

Plasma-derived product comes from blood donors that contains FVIII and VWF. It must be given on the same day as the procedure.

43
Q

A 7-day old baby at home is found unconscious and bleeding from his nose and mouth. Clotting tests show a PT of 98s, APTT of 102s. Fibrinogen 2.9g/L and platelets 288x10^9/L. What is a possible cause and why?

A

Vitamin K deficiency

44
Q

What is the role of Vitamin K?

A

Essential for several carboxylase enzymes within hepatic cells which are necessary for activation of factors 2,7,9,and 10.

45
Q

Where is vitamin K1 produced?

A

In green leaft veggies and broccoli

46
Q

Where is vitamin K2 produced?

A

Gut flora

47
Q

What can vitamin K deficiency cause?

A

Neonatal haemorrhagic disease.

48
Q

What causes VitK in babies typically?

A

All neonate vit K deficient are deficient because it wasn’t infused post-delivery (IntraMuscularly)

Very little VitK in breast milk.

49
Q

What causes VitK deficiency in adults?

A

Any cause of malnutrition or malabsorption

50
Q

Why are babies prone to vitamin K deficiency?

A

No transplacental passage of Vitamin K

Immature liver

Sterile Gut

Very little vitamin K in breast milk

51
Q

A 54 year old publican is admitted with major haematemesis (vomitting blood). Clotting test show 32x PT, 56 second APTT, 1.2g/L fibrinogen, and 56x10^9/L platelets. What is a possible cause?

A

Patient has liver disease and so there is low synthetic function, low vitamin K absorption, low clearance of activated clotting factors.
Hyperfibrinolysis, thrombocytopenia, and acquired platelet dysfunction

52
Q

What is massive transfusion?

A

Replacement of >50% of blood volume in 12-24 hours.

In adults >10 units of packed RBCs and this results in dilution of clotting factors and platelets.

53
Q

What causes coagulopathy to become worse in patients of massive transfusions?

A

Acidosis and hypothermia, calcium deficiency

54
Q

What is Disseminated Intravascular Coagulation?

A

Death Is Coming (DIC has bad prognosis)

Systemic process where blood is exposed to procoagulant factor such as tissue factor.

Massive thrombin generation and widespread coagulation followed by fibrinolysis and depletion of clotting factors.

55
Q

What are some causes for Disseminated Intravascular Coagulation (DIC)?

A

Acute can be caused by sepsis, severe trauma, and complications of pregnancy, as well as snake bite and acute leukemia

Chronically can be caused by cancer

56
Q

What do RBCs look like in DIC?

A

fragmented and damaged

57
Q

How does DIC present in clinic?

A

Bleeding (64%) including spontaneous bleeding from cannula sites

Renal dysfunction (25%)

Hepatic dysfunction (19%)

Respiratory dysfunction (16%)

Shock (14%)

Thrombo embolism (7%)

CNS involvement (2%)

58
Q

What are risk factors for venous thromboembolism?

A

Virchow’s triad:

Endothelial injury

Hypercoagulability

Abnormal blood flow

These 3 result in thrombosis

59
Q

What are the clinical features of deep vein thrombosis?

A

Swelling

Redness

Tenderness

Pitting Oedema (enlargement and swelling of leg where pushing into it leaves a pit there)

60
Q

What is the probability that someone has DVT if they present with the symptoms?

A

1 in 5 people suspected to have DVT actually have it

61
Q

Can DVT be safely diagnosed based on history/exam alone?

A

No

62
Q

What must be done for diagnosis of DVT?

A

Assessment of pre-test probability of DVT

Testing D-dimer

Testing through ultrasound of legs

63
Q

What are D-dimer?

A

When fibrin cross links are broken apart the resulting subunits are called D-dimers

64
Q

What breaks down fibrin into D-dimers?

A

Plasmin

65
Q

Where are D-dimers typically seen?

A

In conditions like DVT, DIC, Infection, malignancy, trauma

They are not enough for DVT diagnosis

66
Q

Why are D-dimers measured?

A

If the D-dimer is negative then it is unlikely to be a DVT

67
Q

What are the clinical features of PE?

A

Chest pain

Shortness of breath

Cough/haemoptysis

Palpitations

Syncope

Non-specific symptomsand objective testing to confirm are required

68
Q

What are some PE differential diagnoses?

A

Chest infection

Cardiac failure

Malignancy

Other

69
Q

How is PE diagnosed?

A

Clinical history/exam

Chest X-Ray/ECG/Full Blood Picture

Pulse oxymetry

D-dimer negative excludes PE

Calculate pre-test probability

Imaging studies (ventilation and perfusion lung scan, CT pulmonary angiogram)

70
Q

What is the natural history of venous thromboembolism (VTE)?

A

Usually starts in calf veins

Majority of symptomatic DVT are proximal

PE usually arise from proximal DVT

71
Q

What is the prognosis of VTE?

A

about 50% of proximal DVT cause PE

10% of symptomatic PE are rapidly fatal

30% of untreated symptomatic non-fatal PE will have a fatal recurrence

72
Q

What is treatment of VTE?

A

Relieve symptoms

Prevent PE

Prevent death

Prevent recurrence

Prevent complications of clotting

Anticoagulation is the mainstay of treatment

73
Q

How long is DVT treated for?

A

3 months is usually enough for most people after surgery

74
Q

What is the risk of DVT coming back after the first occurrence if it was spontaneous?

A

1 - 4% in first year

10% at 5 years

30% at 10 years

These people need to given continuous anticoagulant therapies

75
Q

What are the risk factors for acquired VTE conditions?

A

Previous VTE

Major trauma

Major surgery

Cancer

Nephrotic syndrome

Immobility

Major medical illness with hospitalisation

Central Venous line

Some drugs (tamoxifen)

Pregnancy

Oestrogen

Antophospholipid antibodies

Obesity

Age

76
Q

What are some inherited risk factors for VTE?

A

Antithrombin deficiency

Protein C deficiency

Protein S deficiency

Factor V Leiden mutation

Prothrombin gene mutation

Dysfibrinogenemias

77
Q

What does antithrombin do?

A

Inhibits thrombin and factor X

78
Q

What does protein C and protein S do?

A

Inhibits factor V and factor VIII. If this pathway is inhibited coagulation cascade will keep going unchecked.

79
Q

What does antithrombin do?

A

In absence of heparin it slowly inactivates thrombin. In presence of heparin conformation is changed and thus it rapidly inactivates thrombin

80
Q

How is antithrombin deficiency inherited?

A

Autosomal dominant with variable clinical penetrance

81
Q

How is antithrombin deficiency acquired?

A

liver disease, warfarin therapy, protein loss, and DIC

82
Q

What is protein C?

A

Vitamin K dependent protein dependent on vitamin K.

83
Q

How is protein C deficiency inherited?

A

Autosomal dominant inheritance

84
Q

What form must protein C be in to function?

A

Active protein C form (aPC)

85
Q

What does aPC do?

A

Inactivates Va and VIIIa

86
Q

What enhances protein C function?

A

Protein S

87
Q

What is the inheritance of protein S deficiency?

A

Autosomal dominant

88
Q

What is protein S action dependent on?

A

Vitamin K

89
Q

What are the acquired causes of protein S deficiency?

A

Acquired causes include:

Pregnancy

OCP

Liver disease

Certain drugs

HIV

90
Q

What is the incidence of inherited thrombophilic syndromes in Caucasian populations?

A

antithrombin deficiency: <1%

Protein C deficiency: 1%

Protein S deficiency: 1%

Factor V Leiden: 5%

Prothrombin gene mutation: 3%

91
Q

What is factor V leiden?

A

Point mutation in factor V so protein C can’t inactivate factor V. This condition is also called activated protein C resistance

92
Q

How common is factor V leiden?

A

5%

93
Q

How do risk factor effects combine for VTE?

A

Combination of risk factors is very powerful in combination with each other.

IMED2002 UWA (29 decks)

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