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IMED2002 > 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
Is bleeding in haemophilia A and B the same?
Yes, very similar
26
What kind of genetic inheritance does haemophilia follow?
X-linked recessive making it more likely in males
27
How is haemophilia diagnosed?
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)
28
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?
Haemophilia A
29
How is haemophilia managed?
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.
30
What do patients with haemophilia have which details their diagnosis?
A haemophiliac card
31
What are the common differences between platelet defects and clotting factor deficiencies?
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
32
Do people with platelet defects bleed severely after minor cuts?
Yes
33
Do people with clotting factor deficiencies bleed severely after minor cuts?
Not usual
34
Which patients have petechiae typically; platelet defect patients or clotting factor deficient patients?
Platelet defect patients
35
Which factor is a carrying factor of factor 8?
Von-Willebrand factor
36
How is Von-Willebrand's disease inherited?
Autosomal dominant condition found in 1% of the population
37
What are the types of VWD?
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)
38
How is VWD diagnosed in the lab?
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
How is VWD treated?
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
What is DDAVP?
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
What is Tranexemic acid?
Stabilizes fibrin clot which may be taken for first 4 - 5 days after the procedure.
42
What is biostate? How is it made?
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
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?
Vitamin K deficiency
44
What is the role of Vitamin K?
Essential for several carboxylase enzymes within hepatic cells which are necessary for activation of factors 2,7,9,and 10.
45
Where is vitamin K1 produced?
In green leaft veggies and broccoli
46
Where is vitamin K2 produced?
Gut flora
47
What can vitamin K deficiency cause?
Neonatal haemorrhagic disease.
48
What causes VitK in babies typically?
All neonate vit K deficient are deficient because it wasn't infused post-delivery (IntraMuscularly) Very little VitK in breast milk.
49
What causes VitK deficiency in adults?
Any cause of malnutrition or malabsorption
50
Why are babies prone to vitamin K deficiency?
No transplacental passage of Vitamin K Immature liver Sterile Gut Very little vitamin K in breast milk
51
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?
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
What is massive transfusion?
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
What causes coagulopathy to become worse in patients of massive transfusions?
Acidosis and hypothermia, calcium deficiency
54
What is Disseminated Intravascular Coagulation?
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
What are some causes for Disseminated Intravascular Coagulation (DIC)?
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
What do RBCs look like in DIC?
fragmented and damaged
57
How does DIC present in clinic?
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
What are risk factors for venous thromboembolism?
Virchow's triad: Endothelial injury Hypercoagulability Abnormal blood flow These 3 result in thrombosis
59
What are the clinical features of deep vein thrombosis?
Swelling Redness Tenderness Pitting Oedema (enlargement and swelling of leg where pushing into it leaves a pit there)
60
What is the probability that someone has DVT if they present with the symptoms?
1 in 5 people suspected to have DVT actually have it
61
Can DVT be safely diagnosed based on history/exam alone?
No
62
What must be done for diagnosis of DVT?
Assessment of pre-test probability of DVT Testing D-dimer Testing through ultrasound of legs
63
What are D-dimer?
When fibrin cross links are broken apart the resulting subunits are called D-dimers
64
What breaks down fibrin into D-dimers?
Plasmin
65
Where are D-dimers typically seen?
In conditions like DVT, DIC, Infection, malignancy, trauma *They are not enough for DVT diagnosis*
66
Why are D-dimers measured?
If the D-dimer is negative then it is unlikely to be a DVT
67
What are the clinical features of PE?
Chest pain Shortness of breath Cough/haemoptysis Palpitations Syncope Non-specific symptomsand objective testing to confirm are required
68
What are some PE differential diagnoses?
Chest infection Cardiac failure Malignancy Other
69
How is PE diagnosed?
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
What is the natural history of venous thromboembolism (VTE)?
Usually starts in calf veins Majority of symptomatic DVT are proximal PE usually arise from proximal DVT
71
What is the prognosis of VTE?
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
What is treatment of VTE?
Relieve symptoms Prevent PE Prevent death Prevent recurrence Prevent complications of clotting Anticoagulation is the mainstay of treatment
73
How long is DVT treated for?
3 months is usually enough for most people after surgery
74
What is the risk of DVT coming back after the first occurrence if it was spontaneous?
1 - 4% in first year 10% at 5 years 30% at 10 years These people need to given continuous anticoagulant therapies
75
What are the risk factors for acquired VTE conditions?
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
What are some inherited risk factors for VTE?
Antithrombin deficiency Protein C deficiency Protein S deficiency Factor V Leiden mutation Prothrombin gene mutation Dysfibrinogenemias
77
What does antithrombin do?
Inhibits thrombin and factor X
78
What does protein C and protein S do?
Inhibits factor V and factor VIII. If this pathway is inhibited coagulation cascade will keep going unchecked.
79
What does antithrombin do?
In absence of heparin it slowly inactivates thrombin. In presence of heparin conformation is changed and thus it rapidly inactivates thrombin
80
How is antithrombin deficiency inherited?
Autosomal dominant with variable clinical penetrance
81
How is antithrombin deficiency acquired?
liver disease, warfarin therapy, protein loss, and DIC
82
What is protein C?
Vitamin K dependent protein dependent on vitamin K.
83
How is protein C deficiency inherited?
Autosomal dominant inheritance
84
What form must protein C be in to function?
Active protein C form (aPC)
85
What does aPC do?
Inactivates Va and VIIIa
86
What enhances protein C function?
Protein S
87
What is the inheritance of protein S deficiency?
Autosomal dominant
88
What is protein S action dependent on?
Vitamin K
89
What are the acquired causes of protein S deficiency?
Acquired causes include: Pregnancy OCP Liver disease Certain drugs HIV
90
What is the incidence of inherited thrombophilic syndromes in Caucasian populations?
antithrombin deficiency: <1% Protein C deficiency: 1% Protein S deficiency: 1% Factor V Leiden: 5% Prothrombin gene mutation: 3%
91
What is factor V leiden?
Point mutation in factor V so protein C can't inactivate factor V. This condition is also called activated protein C resistance
92
How common is factor V leiden?
5%
93
How do risk factor effects combine for VTE?
Combination of risk factors is very powerful in combination with each other.

IMED2002 (29 decks)

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