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Haematology > Bleeding disorders > Flashcards

Bleeding disorders Flashcards

1
Q

Bleeding disorders are split into 3 categories, what are they?

A
  1. vascular defects
  2. platelet disorders
  3. coagulation disorders
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2
Q

What are some vascular defects that cause bleeding disorders?

A

Connective tissue disorders: Marfan’s, Ehlers-Danlos

Infection
Drugs
Allergies
These can all damage the vessels

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3
Q

How does a vascular defect cause a bleeding disorder?

A

The vessels become damaged and leaky, causing bleeding into muscle, skin, organs etc.

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4
Q

What is purpura?

A

A purple rash on the skin caused by micro-bleeds into the skin

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5
Q

What are some platelet defects that cause bleeding disorders?

A

Thrombocytopenia

Decreased production by bone marrow: aplastic anaemia

Renal and liver disease

Drugs

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6
Q

What are some coagulation defects that cause bleeding disorders?

A

Haemophilia
Von Willebrand’s disease

Over-anticoagulation
Liver disease
Disseminated intravascular coagulation

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7
Q

How does aplastic anaemia cause bleeding disorder?

A

Aplastic anaemia is when the bone marrow fails to produce many RBCs, WBCs and platelets

Fewer platelets in the blood = bleeding disorder

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8
Q

Why does fewer healthy platelets in the blood cause a bleeding disorder?

A

Without platelets, the body cannot form clots meaning if there is vessel injury blood will leak out without being stopped by a clot formation

This can lead to lots of small micro-bleeds or haemorrhage

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9
Q

Why do bleeding disorders cause bruising?

A

Because bleeding disorders cause bleeding into skin, that is not stopped by clotting

Bleeding into skin is what causes the discolorations we call bruises

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10
Q

How does renal failure cause bleeding disorder?

A

Renal failure will result in a build up of urea in the blood stream - uraemia

Urea is able to damage platelets, meaning they won’t work properly, so bleeding disorder occurs

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11
Q

Which drug is known to cause platelet defects? How?

A

Aspirin

It blocks the formation of thromboxane, which means that platelet aggregation is inhibited

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12
Q

What is thromboxane?

A

Cytokines responsible for the aggregation of platelets that form blood clots.

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13
Q

How does liver failure cause bleeding disorders?

A

Thrombopoietin is a hormone which regulates platelet production

Thrombopoietin is produced by the liver hepatocytes and the kidneys

When liver cell mass is severely damaged, you get reduced thrombopoiesis in the bone marrow

This results in insufficient platelets in the blood of patients with liver failure

PLUS reduced production of clotting factors

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14
Q

What is thrombopoietin, and where is it produced?

A

A hormone that regulates platelet production

Produced in liver hepatocytes and kidney

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15
Q

What are platelets?

How are they formed?

A

Anucleate cells, formed by fragmentation of megakaryocyte cytoplasm in the bone marrow

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16
Q

What is the role of platelets?

A

Haemostasis, they help form blood clots, which prevent excessive bleeding

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17
Q

How long do platelets live?

A

7-10 days

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18
Q

What are the clinical features of platelet defects?

A

Mucosal bleeding:

  • gums
  • menorrhagia (heavy bleeding)
  • epistaxis (nose bleeds)

Easy bruising

Petechiae, purpura

Traumatic haematomas:
- subdural

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19
Q

What’s the difference between petechiae and purpura?

A

Petechiae are smaller than purpura

But they are both small reddish-purple lesions

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20
Q

What is thrombocytopenia?

A

An umbrella term for many conditions which cause reduced number of platelets in the blood

Can be due to decreased production OR increased destruction

Can be inherited or acquired

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21
Q

What two reasons cause thrombocytopenia to develop?

A

Decreased production

Increased destruction

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22
Q

List some causes of thrombocytopenia caused by decreased production?

A

Congenital

Infiltration of bone marrow:

  • leukaemia
  • myeloma
  • lymphoma

Aplastic anaemia

Low B12 / folate
Reduced TPO: liver disease
Medication
Toxins
Infections, usually viral
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23
Q

How do malignancies of the bone marrow cause thrombocytopenia?

A

Decreased production of platelets

Damage to bone marrow = damage to blood stem cells
So reduced/dysfunctional production of platelets

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24
Q

Name a condition that causes thrombocytopenia caused by dysfunctional production of platelets in the bone marrow?

Briefly describe it?

A

Myelodysplasia

The bone marrow produced abnormal blood cells and platelets that are not yet fully developed

25
Q

List some causes of thrombocytopenia caused by increased destruction?

A

Autoimmune conditions:

  • ITP
  • TTP
  • secondary: SLE

Hypersplenism

Drugs

Disseminated intravascular coagulopathy

Haemolytic uraemic syndrome

26
Q

How does SLE cause thrombocytopenia?

A

Increased destruction of platelets

Autoantibodies attack host antigens, including the ones on platelets, destroying them

27
Q

What is hypersplenism and how does it cause thrombocytopenia?

A

Hypersplenism: the spleen becomes overactive and starts removing more RBCs and platelets than it should

Increased destruction of platelets causes thrombocytopenia

28
Q

What causes hypersplenism?

A

Splenomegaly of any cause

Portal hypertension

29
Q

Which drug is well known to cause thrombocytopenia? How?

A

Heparin: a fast acting anti-coagulant

Administration to patients can cause Heparin Induced Thrombocytopenia (HIT)

Heparin is naturally occurring in the body, in HIT autoantibodies are produced against platelets, destroying them

30
Q

What is immune thrombocytopenic purpura?

A

An autoimmune disorder that causes destruction of platelets by autoantibodies

This leads to bleeding disorder

31
Q

What is the difference in aetiology of ITP in adults and children?

A

Immune thrombocytopenic purpura

Children: acute and self-limiting, often triggered by a viral infection

Adults: chronic, occurs with malignancies, or with other autoimmune disorders like SLE

32
Q

Clinical features of ITP?

A

Bleeding:

  • bruising
  • menorrhagia
  • epistaxis

Purpura

33
Q

Treatment of ITP?

A

Treat the underlying cause

Immunosuppressants: steroids, IV immunoglobulins

Give platelets for temporary relief of bleeding

Tranexamic acid

34
Q

What is transexamic acid used to treat? And how does it do it?

A

Immune thrombocytopenic purpura

Inhibits breakdown of fibrin
Good for treating mucosal bleeding

35
Q

What does ITP and TTP stand for?

A

ITP = immune thrombocytopenic purpura

TTP = thrombotic thrombocytopenic purpura

36
Q

What is TTP?

A

Widespread adhesion and aggregation of platelets in small vessels

Causes microvascular thrombosis AND thrombocytopenia (because all the platelets are caught up in the clot)

37
Q

What causes TTP?

A

Deficiency of ADAMTS 13, a protease

Caused by an autoantibody that attacks ADAMTS 13

Can be congenital or acquired

38
Q

What are some acquired causes of TTP?

A

Pregnancy
SLE
Infection
Drugs

39
Q

Clinical features of TTP?

A

Purpura

Fever
Fluctuating cerebral dysfunction
Haemolytic anaemia

40
Q

Investigation of TTP?

A

Raised lactate dehydrogenase in blood

41
Q

Treatment of TTP?

A

Plasma exchange to remove autoantibody

Steroids and biological DMARDs

42
Q

What is DIC?

A

Disseminated intravascular coagulopathy

Widespread activation of the clotting cascade
Blood clots form in the small blood vessels of the body
This leads to disrupted blood flow in organs and organ damage

43
Q

How does DIC cause thrombocytopenia?

A

The widespread clotting that occurs in DIC uses up all the platelets in the clots

Few are left over, causing thrombocytopenia, leading to bleeding in other sites of the body

44
Q

What is haemophilia?

A

An inherited disorder causing a deficiency of one of the coagulation factors

Haemophilia A + B

45
Q

Haemophilia A is a deficiency of what?

A

Coagulation factor VIII

46
Q

What is the inheritance pattern of Haemophilia?

A

X-linked recessive

47
Q

Haemophilia B is a deficiency of what?

A

Coagulation factor IX

48
Q

Which Haemophilia is also known as Christmas disease?

A

Haemophilia B

49
Q

Clinical features of Haemophilia A + B?

A

Mild: excess bleeding after trauma or surgery

Moderate: severe bleeding following minor injury and occasional spontaneous episodes of bleeding

Severe: frequent spontaenous bleeding into joints and muscles, which can lead to crippling arthropathy

All are at increased risk of haemorrhage

50
Q

Investigations of Haemophilia?

A

Prolonged APTT (a test to see how long your blood takes to clot)

Reduced levels of factor VIII (A) or factor IX (B)

51
Q

What is APTT?

A

Activated partial thromboplastin time

It is a test to see how long your blood takes to clot

52
Q

Management of Haemophilia A?

A

IV infusion of recombinant factor VIII

  • prophylactically
  • use on first signs of bleeding

Synthetic vasopressin (desmopressin) increased factor VIII levels

53
Q

Management of Haemophilia B?

A

Factor IX concentrates

Desmopressin is not helpful

54
Q

What is von Willebrand’s disease?

A

Deficiency of von Willebrand factor, causing defective platelet function

55
Q

Why does vitamin K deficiency cause bleeding disorder?

A

Vitamin K is needed for formation of coagulation factors II, VII, IX, X

56
Q

What is meant by over-anticoagulation?

A

Too high a dose of anti-coagulation drugs, such as warfarin

The right balance has not been struck between too much or too little blood clotting, and too little clotting is occurring

Leading to bleeding disorder

57
Q

What is INR?

A

International normalised ratio

Test used to check how long blood takes to clot
Used to monitor people taking warfarin

58
Q

The higher the INR…

A

The longer the blood is taking to clot

Haematology (9 decks)

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