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Haematology Sem 1 > Disorders of Haemostasis > Flashcards

Disorders of Haemostasis Flashcards

1
Q

What causes disorders of haemostasis?

A

Deficiencies of coagulation factors that cause excessive bleeding

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2
Q

What are the two subcatergories of bleeding disorders?

A

Hereditary and aquired

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3
Q

What causes coagulation factor disorders?

A

Low levels of coagulation factors of disfunctional coagulation factors

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4
Q

What are general symptoms of bleeding disorders?

A

bleeding gums, bruises, purpura (blood spots) petichae, menorrhagia, joint bleeds, muscle bleeds, anaemia

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5
Q

What are the 4 main hereditary blood disorders:

A

Haemophilia A, Haemophilia B, Haemophilia C and Von Willebrand Factor Disease

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6
Q

What is Haemophilia A

A

Deficiency of FVIII (which is a cofactor for thrombin amplification)
It is either absent or in low levels.
The severity of the disorder depends on the severity of VIII deficiency.
NR: 50-150 IU/DL. 50% of cases have <1.0 IU/DL

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7
Q

What is the genetics behind Haemophilia A

A

X linked

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8
Q

What is the prevelance of haemophilia A?

A

Mostly in males, 1:10,000 males. 30% is spontaneous as no family history

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9
Q

What causes Haemophilia A?

A

Most common= inversion mutation of FVIII gene on intron 22. This results in total elimination of protien production with carying clinical severity

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10
Q

What are the symptoms of haemophilia A?

A

Begins in infancy: excessive bleeding after circumcision, excessive bruising once child becomes active
Muscle haematomas: abnormal collection of blood outside of blood vessel of muscle
Haemathroses: bleeding into joint spaces which damages the muscle as the blood pools in
Bleeds into the internal organs
Post-op and post-trauma haemorrhaging can be life threatening

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11
Q

What is haemophilia B?

A

Absence or low levels of IX.

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12
Q

Why is haemopholia B the same symtoms and prevelance?

A

Because IX and VIII are directly linked > VIII is cofactor for IXa.

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13
Q

How would you distinguish between haemophilia A and haemophilia B?

A

FIX assay - measuring the FIX levels

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14
Q

What is haemophilia C?

A

Deficiency of XI. It has variabe clinical severity and bleeding does not correlate with levels of XI. 8% of ashkenazi jews have FXI deficiency

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15
Q

Where is haemophilia treated?

A

specialised haemophilia centres

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16
Q

What is the treatment of haemophilia?

A

Prophalactic factor infusion theraphy (Factor infused directly into blood stream. Must be done 3x per week and can be done from home. Generally its recombinent genetically engineered factors. Increases levels from <1IU/L to >1IU/L

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17
Q

What does treatment of haemophilia achieve?

A

Stops crippling haemathroses. Although specialise care when post srugery and spontaneous bleeds, life expectancy is almost normal although contact sport not recommended without porphalxis.

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18
Q

How is haemophilia diagnosed in the labs?

A 
Activated partial thromboplastin time test (APTT) which measures the intrinsic coagulation pathway. An extended of time indicates XII XI IX and VIII deficiency.
Prothrombin time (PT) measures the extrinsic coagulation pathway. Abnormal times indicate VII synthesis so in haemophilia patients, PT should be normal
Assay used to measure levels of coagulation factor - coagulation factor will be reduced
Platelet function should be normal and bleeding time should be normal
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19
Q

What is the most common hereditary bleeding disorder

A

von willebrands disease - 1% of the population

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20
Q

What does vW disease cause?

A

Usually very mild symptoms, severity dependant on subtype. ‘pseudo’ haemophilia due to no haemathroses.

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21
Q

What causes vW disease?

A

qualative and quantiative defects of vWF either through abnormal levels of functioning vWF or normal levels of abnormal vWF.

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22
Q

What kind of inheritance is vWD?

A

autosomal dominant . Men and women affected but mostly women

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23
Q

What are the three subtypes of von willebrand disease?

A

Type 1- mild reduction of vWF
Type 2- functionally abnormal vWF
Type 3- total absence of vWF

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24
Q

What are the symtoms of vWD?

A

Mild to moderate bleeding disoders. More nosebleeds (epitaxis) and easy bruising. Excessive minor wound bleeds and heavy menstruation. Rarely life threatening. Haemathroses and muscle haematomas is rare except in type 3

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25
Q

What is the role of vWF?

A

Promote platelet adhesion, protect factor VIII from premature destruction.. This explains longer APTT time being extended as without vWF, VIII will be destroyed more which means there is a deficiency

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26
Q

What are the lab findings in vWD?

A

Abnormal platelet function test, defective platelet aggregation, low FVIII levels. APTT extended due to affected intrinsic pathway. vWF low. Low platelet count in type 2

27
Q

What is the treatment for VW disorder

A

Type 1: DDAVP (vasopressin): releases vWF from endothelial cells
Type 2: Plasma derived vWF/FVIII concentrated. Recombinant vWF in phase 2 of clinical trials

28
Q

What are other clotting factor deficiencies?

A

Fibrinogen disfunction (FI,FVII,FV) (1 in a million) and prothrombin (FII, FXIII) (1 in 2 million). Both autosomal recessive except fibrinogen. Common in ccountried where marriage between relatives in common

29
Q

What are the two subcategories of aquired bleeding disorders?

A 
Production dysfunction (Vit K deficienct, liver disease)
Consumption dysfunctions (disseminated intravascular coagulation - DIC)
30
Q

What is vitamin K?

A

Fat soluble vitamin obtained from green vegetables

31
Q

Where is vitamin K synthesised?

A

By bacteria in the gut

32
Q

What causes it?

A

Can be present at birth (haemorrhaging disease of the newborn) or caused by inadequate diet, malabsorption, drugs.

33
Q

What will cause vitamin K deficiency?

A

II,VII,IX,X

34
Q

What will lab findings show?

A

extended PT and APTT

35
Q

What causes liver disease? Lab findings?

A

Impaired absorption of vit K. Decreases synthesis of II,VII,,IX,X. Prolonged PT and APTT due to disruption of intrinsic and extrinsic pathways

36
Q

What is disseminated intravascular coagulation disorder? What does it cause?

A

Microcoagulation in blood vessels. Usually secondary disorder to sepsis, malignanct, AML,snake venom.
Causesd by excess TF triggering leading to excess acitvation of coagulation. Fibrin is desposited into microcirculation which can lead to amputation.
Haemorrhage due to consumption of coagulation factors.

37
Q

What is an aquired inhibitor of coagulation?

A

Inhibitor of FVIII (acquired haemophilia) which occurs in elderly patients with underlying condition (usually malignancy)

38
Q

What are the two subcategories of platelet disorder?

A

Hereditary/congenital

Acquired

39
Q

What are the three main platelet disorders?

A

Glanzmannz disease
Bernard soilier
vWB disorder

40
Q

What is glanzmannz disorder?

A

Failure of primary platelet aggregation in vivo. Clinically severe platelet function defecit

41
Q

What kind of inheritance is glanamannz disorder?

A

Autosomal recessive inheritance

42
Q

What would the lab show of glanzmannz disorder?

A

Normal platelet count, deficienct of GPIIbIIIa membrain protien

43
Q

What are the symptoms of glanzmannz disorder?

A

Epitaxis, purpura, bruising, gum bleeding, menorrhagia, bleeding after surgery

44
Q

What is bernard soulier syndrome?

A

Absense or depletion of GPIb-V-IX complex on platelet surface causing defective binding with vWF. Platelets have defective aherance ot subendothelial connective tissues

45
Q

What are the clinical features/lab ones

A

Variable degrees of thrombocytopenia (depletion of WBC) and platelets are large. Bleeding more severe than is expected for that degree of thrombocytopenia

46
Q

What are the three subcategories of aquired platelet disorders?

A

Production, Shortened life span, function

47
Q

What drugs affect platelet function?

A

Alcohol, asprin, caffeine, anitmicrobials, anticoagulants

48
Q

What is thrombosis?

A

Formation of a solid mass (thrombus) in the lumen of a blood vessel. The mass is formed of platelets, fibrin and blood.

49
Q

What a thrombus attatched to?

A

A vessel wall

50
Q

What are the two types of thrombosis?

A

Venous thrombosis, aterial thrombosis

51
Q

What is thrombosis assosicated with?

A

Myocardial infarction, cerebral vascular disease, deep vein thrombosis and pulmonary embolism

52
Q

What are the three main stages of thrombus formation?

A

Statis of blood (stasis), hypercoagulability of blood (more coagulation) and vessel wall damage

53
Q

What is the pathogenesis of arterial thrombosis?

A

Atherosclorosis of vessel wall. This injury to the vessel wall exposes blood to subendothelial collagen and tissue factor. this will be the nidus/loci of the thrombbosis (so where platelets will adhere to and aggregate. Artery eventually blocks.

54
Q

What are the risk factors for arterial thrombosis?

A

Being male, family history, raised lipids, raised BP, diabetes, smoking.

55
Q

What is the pathogenesis of venous thrombosis?

A

The coagulability of blood increases so blood flow slows down. The thrombus initiates where the site of coagulation is occuring

56
Q

What are the risk factors for venous thrombosis?

A

FV mutation. Prothrombin gene mutation. Protein S or C mutation. ABO blood group. Raised fibrinogen. Oral contraception, pregnanct age, immobility

57
Q

What is herediary thrombophilia

A

Occurs in young people with spontaneous thrombosis. Thrombus occurs at an irregular site and regular deep vein thrombosis

58
Q

What is a factor V mutation?

A

most common cause of venous thrombosis
argenine replaced with glutamine on Fv gene
Heteroxygous makes thromobosis 8 x more likely. Homozygous makes it 140 times more likely.

59
Q

What is antithrombin deficiency?

A

autosomal dominant. Recurrent venous thrombosis throughout early adult life. Given through surgery and child birth to stop thrombosis
deficiency leads to a 10 x increased risk of thrombosis

60
Q

What is a protien S or C deficiency?

A

C is Autosomal dominant
Activated by thrombin
Cleave V and VIII to inactivate them
Heterozygous inheritance increased risk of thrombosis by 10 fold (reduced by 50%)
Homozygous inheritance is life threatening
Causes massive thrombopoeitic complications soon after birth
Protien S linked to thrombosis as cofactor for protien C
Deficieincy increases chace of thrombosis by 10 x

61
Q

Prothrombin gene mutation?

A

Increased numbers of prothrombin in circulation. 2-3 fold icrease if heterozygous inheritance

62
Q

ABO blood group?

A

None O have a higher risk of thrombosis formation due to higher vWF and FVIII

63
Q

What is the treatment of thrombosis?

A

Heparin (low molecular weight)
Drug during pregnancy that does not pass through placenta
Oral anticoagulant - warfrin

Haematology Sem 1 (8 decks)

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