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Y2 - HAEM > Abnormalities in Haemostasis > Flashcards

Abnormalities in Haemostasis Flashcards

1
Q

Give some common causes of minor bleeding symptoms, including those seen only in women. Don’t worry if you don’t get them all, don’t need to be too stressed about it, just like idk suggest some

A
  • Easy bruising
  • Gum bleeding
  • Frequent nosebleeds
  • Bleeding after tooth extraction
  • Post-op bleeding
  • FHx

Women:

  • Menorrhagia
  • Post-partum bleeding
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2
Q

What might you see in a history that consitute a siginificant bleeding history (don’t worry about getting all of these)?

A
  • Epistaxis not stopped by 10 mins compression or requiring medical attention/transfusion
  • Cutaneous haemorrhage or bruising without apparent trauma (esp. multiple/large)
  • Prolonged (>15 mins) bleeding from trivial wounds, or in oral cavity or recurring spontaneously in 7 days after wound. Spontaneous GI bleeding leading to anaemia
  • Menorrhagia requiring treatment or leading to anaemia, not due to structural lesions of the uterus
  • Heavy, prolonged or recurrent bleeding after surgery or dental extractions
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3
Q

What does primary haemostasis refer to?

A

Formation of the unstable platelet plug

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4
Q

What does secondary haemostasis refer to?

A
  • Stabilisation of the unstable platelet plug with fibrin
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5
Q

In disorders of primary haemostasis, what 3 components of the primary haemostatic response may be defective?

A
  1. Platelets
  2. vWF (von Willebrand Factor)
  3. Vessel Wall
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6
Q

How might platelet defects or platelet involvement cause disorders of primary haemostasis - give the 3 mechanistic classifications and then the conditions or whatever specifics within them that cause the primary haemostatic defects? Including the 3 hereditary platelet defects

A

Thrombocytopaenia - low numbers

  • Bone marrow failure, so megarkaryocytic failure - e.g. malignancy (leukaemia), megaloblastic anaemia (B12 deficiency)
  • Accelerated clearance of platelets - e.g. ITP (autoimmune thrombocytopaenia), DIC
  • Pooling and destruction in an enlarged spleen - splenomegaly, hypersplenism

Impaired platelet function - hereditary

  • Hereditary absence of glycoproteins or storage granules

Impaired platelet function - due to drugs

  • Aspirin, NSAIDS, clopidogrel impair platelet function (aspirin is a COX1 inhibitor and clopidogrel is a ADP receptor antagonist)

3 hereditary platelet defects

  • Glanzmann’s thrombasthenia - lack of GlpIIa and GlpIIIa, autosomal recessive
  • Bernard Soulier syndrome - lack of GlpIb, autosomal recessive
  • Storage Pool disease - issues with granular storage within platelets - dense granules containing ADP etc
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7
Q

Describe the pathophysiology of auto-ITP (autoimmune thrombocytopaenia purpura)

A
  • Antiplatelet autoantibodies bind platelets by binding the GlpIIb / GlpIIIa receptors
  • These platelets are cleared by the reticulo-endothelial system, by macrophages ultimately
  • This excessive clearance of platelets causes thrombocytopaenia and thus associated symptoms
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8
Q

How can problems with vWF cause problems with primary haemostasis - i.e what are the different types and pathophysiologies behind von Willebrand Disease - 4 of them. Also give their inheritance patterns

A
  1. Type 1 vWD: Make some vWF but still deficient - autosomal dominant or recessive
  2. Type 2 vWD: Defective vWF - autosomal dominant
  3. Type 3 vWD: Make no vWF - autosomal recessive
  4. Autoimmune: Antibodies created against vWF
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9
Q

Give 2 functions of vWF in haemostasis - one is a primary haemostatic role and one is a secondary haemostatic role (less important of its roles)

A
  1. Binding to collagen and capturing platelets
  2. Stabilising factor for VIII - factor VIII may be low if vWF is low
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10
Q

Give heritable and acquired defects of the vessel wall that cause problems with primary haemostasis

A

Inherited

  • Hereditary Haemorrhagic Telangiectasia
  • Ehler’s-Danlos Syndrome
  • Other connective tissue disorders

Acquired

  • Scurvy
  • Steroid therapy
  • Vasculitis
  • Senile purpura
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11
Q

What are some signs that are patterns of bleeding in people with primary haemostatic defects - don’t worry about getting them all just be chill

A
  • Immediate, prolonged bleeding
  • Easy bruising
  • Nosebleeds (prolonged: >20 mins)
  • Gum bleeding (prolonged)
  • Menorrhagia (anaemia)
  • Bleeding after trauma/surgery
  • Petechiae (specific for thrombocytopenia)
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12
Q

What are petechiae and what are they characteristic of?

A
  • Spontaneously occuring small blood spots (smallest type of purpuric lesions) that are characteristic of thrombocytopaenia
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13
Q

Purpura, petechiae and ecchymoses are all types of purpura lesions, but what’s the difference?

A
  • Different sizes
  • SMALLEST: Petechiae
  • MEDIUM: Purpura
  • LARGEST: Ecchymoses
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14
Q

Give 5 tests for disorders of primary haemostasis

A
  1. Platelet count
  2. Platelet morphology
  3. Bleeding time (PFA100 in lab)
  4. Assays of vWF
  5. Clinical observation
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15
Q

Why do people with disorders of secondary haemostasis have delayed bleeding?

A

Because their platelet plug forms properly in primary haemostasis, which forms a temporary haemostatic plug, but since it is unstable, upon high shear it very quickly falls apart without the stabilising fibrin mesh which assembles in secondary haemostasis

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16
Q

Defects of secondary haemostasis are effectively defects of ….. ….. and thus ….. ….. ….. due to deficiency of coagulation factors

A

Defects of secondary haemostasis are effectively defects of thrombin generation and thus fibrin mesh formation due to deficiency of coagulation factors

17
Q

Give 5 reasons for deficiencies of coagulation factors that cause defects in secondary haemostasis

A
  1. GENETIC - HAEMOPHILIA A / B - FVIII / FIX deficiency
  2. LIVER DISEASE - most coagulation factors synthesised in the liver so disease causes deficiency, but also causes deficiency in anti-coagulant factors too
  3. DRUGS - e.g. warfarin - inhibits coagulation factor synthesis
  4. DILUTION - volume replacement; red cell (+platelet) transfusions not containing plasma, so dilution of coagulation factors resulting in deficiency
  5. CONSUMPTION - DIC etc (disseminated intravascular consumption)
18
Q

Match the following coagulation factor deficiencies - defects of secondary haemostasis with their severity:

DEFECTS:

a) Haemophilia (FVIII & FIX deficiency)
b) Prothrombin deficiency (FII)
c) Factor XI deficiency
d) Factor XII deficiency

SEVERITIES:

No excess bleeding at all, severe and spontaneous but compatible with life, bleeding lots after trauma but not spontaneously, lethal

A

a) Haemophilia - severe and spontaneous but compatible with life
b) Prothrombin deficiency - lethal
c) Factor XI deficiency - bleeding lots after trauma but not spontaneously
d) Factor XII deficiency - no excess bleeding at all

19
Q

1) Describe the pathophysiology of DIC (disseminated intravascular coagulation)
2) What causes is DIC associated with?

A

1)

  • Generalised activation of coagulation - tissue factor is activated → uncontrolled coagulation → consumes and depletes coagulation factors and platelets → and depletion of fibrinogen due excess fibrinolysis resulting in FDP increase and fibrin deposition in vessels causing organ failure
20
Q

Describe the pattern of bleeding in people with defects of secondary haemostasis

A
  • Bruise easily
  • Delayed bleeding
  • Stop-start bleeding
  • Superficial / small cuts are OK - dealt with by primary haemostasis
  • Deeper bleeding - into joints etc
  • Bleeding after surgery and intramuscular injections is prolonged
21
Q

1) What is the pathophysiology of haemophilia?
2) What is a characteristic sign of haemophilia?

A

1) Deficiency in FVIII or FIX
2) Haemarthrosis - bleed into joints, pressure builds, swelling and pain

22
Q

Give the tests for defects in secondary haemostasis

A
  • APPT & PT
  • Full blood count
  • Factor assay
  • Test for inhibitors
23
Q

1) What do APPT and PT test and therefore what will they show in the case of defects of secondary haemostasis?
2) Just for sake of completion, what does TCT test?

A

1)

  • APPT = Activated Partial Thromboplastin Time. Tests intrinsic and common pathways
  • PT = Prothrombin Time. Tests extrinsic pathway
  • APPT will be abnormal due to coagulation factor deficiencies e.g. in haemophilia. This is the intrinsic / common pathway
  • But PT will be normal as TF unaffected

2)

  • Tests the common pathway - specifically tests the conversion of fibrinogen into fibrin
24
Q

Give one hereditary and 2 acquired causes of fibrinolytic disorders - a form of defects of secondary haemostasis

A

Hereditary

  • Antiplasmin deficiency - so lots of plasmin - so lots of breakdown of fibrin - so lots of breakdown of secondary haemostatic plug

Acquired

  • tPA drugs
  • DIC
25
Q

What is the inheritance pattern of haemophilia A / B?

A
  • X-linked recessive
  • So female carriers
  • Males affected
26
Q

What is the inheritance pattern of the different types of vWD (von Willebrand Disease)?

A
  • Type 1 - autosomal dominant
  • Type 2 - autosomal dominant
  • Type 3 - autosomal recessive
27
Q

How can you treat abnormal haemostasis due to thrombocytopaenia or missing factors?

A
  • Replace the missing factors / platelets
28
Q

How to treat abnormal haemostasis due to ITP?

A
  • Immunosuppression e.g. prednisolone
  • Splenectomy
29
Q

Outline the 4 types of factor replacement therapy you can get and describe them

A
  1. Plasma - contains all coagulation factors
  2. Cryoprecipitate - rich in fibrinogen, FVIII, vWF, FXIII
  3. Factor concentrates - available for all factors except FV, prothrombin complex concentrates - FII, VII, IX, X
  4. Recombinant forms of FVIII, IX
30
Q

Describe platelet replacement therapy

A

Pooled platelet concentrates available

31
Q

Give 2 medications that can be used to treat haemostatic defects and how they work

A
  1. DESMOPRESSIN (DDAVP) - releases endogenous stores of FVIII and vWF so useful in haemophilia / vWD
  2. TRANEXAMIC ACID - inhibits fibrinolysis by inhibiting tPA (prevents tPA binding fibrin so prevents tPA’s conversion of plasminogen into plasmin to degrade fibrin in fibrinolysis)
32
Q

How is DDAVP useful in treating haemostatic disorders - what is its mode of action and give 2 disorders it is useful in?

A
  • VP analogue
  • Stimulates release of vWF and FVIII from endogenous stores so more available
  • These are what are defecient of in vWF and Haemophilia A respectively so useful for these
33
Q

How is Tranexamic useful in treating haemostatic disorders - what is its mode of action?

A

Inhibits fibrinolysis by inhibiting tPA (prevents tPA binding fibrin so prevents tPA’s conversion of plasminogen into plasmin to degrade fibrin in fibrinolysis)

34
Q

How might DIC lead to organ failure?

A
  • Increased fibrin deposition

Y2 - HAEM (11 decks)

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