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Yr 4 - Paediatrics > Haem: Immune Thrombocytopenia Purpura & Sickle Cell Anaemia > Flashcards

Haem: Immune Thrombocytopenia Purpura & Sickle Cell Anaemia Flashcards

1
Q

What is a non-blanching rash caused by?

A

Small bleeds in the vessels beneath the skin, giving a purplish discolouration.

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2
Q

How can non-blanching rashes be defined?

A

Depending on size:

1) Petechiae: <5mm diameter
2) Purpura: 5-10mm diameter
3) Ecchymoses: >1cm diameter

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3
Q

What are the 6 most common causes of non-blanching rashes?

A

1) Meningococcal sepsis

2) Henoch-Schönlein purpura

3) Idiopathic thrombocytopaenic purpura (ITP)

4) Haemolytic uraemic syndrome (HUS)

5) Forceful coughing/vomiting

6) Non-accidental injury

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4
Q

What is ITP?

A

Involves the development of a purpuric rash in those with low circulating platelets (<100 x 10⁹/L) in the absence of any clear cause.

ITP is caused by a type II hypersensitivity reaction –> the production of antibodies that target and destroy platelets.

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5
Q

What is ITP caused by?

A

The type II hypersensitivity reaction can happen spontaneously, or it can be triggered by something, such as a viral infection.

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6
Q

What does ITP usually follow in children?

A

Viral illness

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7
Q

Typical clinical features of ITP?

A
  • Prodromal viral illness in children
  • Mucocutaneous bleeding: epistaxis, oral bleeding e.g. buccal/gingival
  • May be asymptomatic
  • Petechiae and/or bruising (non-blanching) –> KEY FEATURE
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8
Q

What is the most typical presentation of ITP?

A

An otherwise well child with a petechial rash alone.

Usually there is a history of a recent viral illness, in approximately 60% of children (e.g. URTI).

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9
Q

What investigations may be relevant in ITP?

A

1) FBC & blood film

2) Bloodborne virus screen (HIV, hep C): to exclude secondary cause of ITP.

3) Bone marrow biopsy: if the diagnosis is uncertain.

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10
Q

What will FBC show in ITP?

A

Thrombocytopenia

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11
Q

Usually, what the the only blood abnormality in ITP?

A

An isolated thrombocytopenia with a platelet count of <100x109/L

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12
Q

WBC in ITP?

A

Should be within normal limits.

If abnormal, should spark suspicion of another condition.

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13
Q

Size of petechiae vs purpura vs ecchymoses?

A

Petechiae - pin prick spots of bleeding under skin, around 1mm

Purpura - larger (3-10mm) spots of bleeding under the skin

Ecchymoses - >10mm, non-blanching lesions where large area of blood has collected

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14
Q

What are 2 other causes of a low platelet count?

A

1) Heparin induced thrombocytopenia

2) Leukaemia

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15
Q

What does management of ITP usually involve?

A

The severity and management depends on how low the platelet count falls.

Usually no treatment is required and patients are monitored until the platelets return to normal.

Around 70% of patients will remit spontaneously within 3 months.

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16
Q

Treatment in ITP may be required if the patient is actively bleeding or severe thrombocytopenia (platelets below 10).

What may treatment involve?

A

1) Stopping any medications which may affect platelets (e.g: nonsteroidal anti-inflammatories)

2) Oral prednisolone is regarded as the first-line treatment

3) IV immunoglobulins (IVIG)

4) Monoclonal antibodies such as rituximab

5) Splenectomy: can be considered once all medical treatment options have been exhausted

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17
Q

Platelet transfusions can be given in ITP, but these only work temporarily.

Why?

A

Because the antibodies against platelets will begin destroying the transfused platelets as soon as they are infused.

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18
Q

What is some key education and advice to give in ITP?

A
  • Avoid contact sports
  • Avoid IM injections and procedures such as lumbar punctures
  • Avoid NSAIDs, aspirin and blood thinning medications
  • Advice on managing nosebleeds
  • Seek help after any injury that may cause internal bleeding, for example car accidents or head injuries
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19
Q

What are some possible complications of ITP?

A

1) Chronic ITP

2) Anaemia

3) Intracranial & subarachnoid haemorrhage

4) GI bleeding

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20
Q

What is sickle cell disease?

A

Genetic condition that causes sickle (crescent) shaped RBCs.

This abnormal shape makes the red blood cells more fragile and easily destroyed, leading to haemolytic anaemia.

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21
Q

Sickle cell disease vs sickle cell anaemia?

A

Sickle cell disease (SCD) is the name given to a group of disorders associated with the deformation of red blood cells into a sickled shape.

Sickle cell anaemia (SCA) is the name given to the most common and serious form of SCD. SCA is caused by the inheritance of two abnormal sickle cell genes.

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22
Q

Which ethnicity is sickle cell most commonly seen in ?

A

African and Caribbean ancestry

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23
Q

What is the most common type of Hb present in the foetus and neonate?

A

HbF

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24
Q

What is HbF composed of?

A

2x alpha chains and 2x gamma chains

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25
Q

What is the most common Hb type present in people >6 months of age?

A

HbA

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26
Q

What is HbA composed of?

A

2x alpha and 2x beta chains

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27
Q

Inheritance of sickle cell?

A

Autosomal recessive

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28
Q

What mutation is present in sickle cell?

A

Single point mutation in the beta-globin gene on chromosome 11.

This results in amino acid replacement in the beta-globin gene, from gutamic acid to valine.

This results in sickled haemoglobin (HbS).

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29
Q

Sickle cell trait vs sickle cell disease?

A

One abnormal copy of the gene results in sickle-cell trait - usually asymptomatic as they are carriers of the condition.

Two abnormal copies result in sickle-cell disease.

30
Q

What is the relationship between sickle cell and anaemia?

A

Having one copy of the gene (sickle cell trait) reduces the severity of malaria (i.e. offers some protection).

Therefore, there is a selective advantage to having the sickle cell gene in areas of malaria, making it more common.

31
Q

What is the problem with having sickle shaped RBCs?

A
  • These cells are fragile and haemolyse
  • They also block small blood vessels and cause infarction
32
Q

Under physiological stress, sickled haemoglobin (HbSS) polymerises and causes erythrocytes to deform into a sickled shape.

What are some physiological stressors?

A

1) Hypoxia
2) Dehydration
3) Infection
4) Cold temperatures
5) Acidosis e.g. lactic acid following exertion

Note - The above stressors do not usually induce sickling in patients with sickle cell trait (HbAS).

33
Q

When is sickle cell screened for?

A

On newborn blood spot test around 5 days of age.

Pregnant women at high risk of being carriers of the sickle cell gene are offered testing.

34
Q

Clinical features of sickle-cell anaemia may be divided up into acute events and chronic complications.

Name some acute complications

A

1) Vaso-occlusive crisis

2) Acute chest syndroome

3) Splenic sequestration crisis

4) Aplastic crisis

5) Haemolytic crisis

6) Priapism

35
Q

When do clinical features of sickle cell typically begin?

A

Around 3-6 months of age - as this is when HbF levels fall and the proportion of HbSS rises.

36
Q

What is the most common reason for hospital admission among sickle cell patients?

A

Vaso-occlusive crisis

37
Q

What is a vasoocclusive crisis in sickle cell?

A

Where sickled RBCs obstruct the microcirculation, lead to severe pain and ischaemia +/- infarction.

38
Q

Commonly affected sites in a vaso-occlusive crisis?

A
  • Bones (long bones and vertebrae): bone pain & avascular necrosis
  • Joints: painful swollen joints & dactylitis
  • Lungs: SOB, chest pain, tachypnoea (up to 30% mortality in adult patients)
  • Brain: headaches & strokes
39
Q

What is acute chest syndrome?

A

A life-threatening complication of sickle cell.

This may result from vaso-occlusion in pulmonary vasculature or infection leading to pneumonia.

40
Q

Features of acute chest syndrome?

A
  • fever
  • tachypnoea
  • SB
  • cough
  • sputum production
  • new onset hypoxia
41
Q

How will acute chest syndrome present on a CXR?

A

New pulmonary infiltrates

42
Q

What is aplastic crisis in sickle cell?

A

The temporary cessation of erythropoiesis, causing severe anaemia.

Patients may present with high-output congestive heart failure secondary to anaemia.

43
Q

What are aplastic crises usually precipitated by?

A

Infection with parvovirus B19 (this temporarily halts erythropoiesis).

44
Q

What is usually required for management of aplastic crisis?

A

A transfusion is usually required but recovery may also occur spontaneously.

45
Q

What is a sequestrian crisis in sickle cell?

A

The sudden enlargement of the spleen due to haemorrhage within it.

This is associated with an acute drop in Hb and a markedly raised reticulocyte count.

46
Q

Blood results in sequestration crisis?

A

Acute drop in Hb and markedly raised reticulocyte count.

47
Q

How can sequestration crisis present?

A

Sequestration may lead to circulatory collapse and hypovolemic shock.

Occurs mainly in babies and young children.

48
Q

What is recurrent splenic sequestration an indication for?

A

Splenectomy

49
Q

What are some chronic complications of sickle cell?

A

1) Anaemia

2) Infections

3) Leg ulcers

4) Ocular complications

5) Renal complications

6) CVS complications

50
Q

What type of anaemia is seen in sickle cell?

A

Chronic haemolytic anaemia is a constant feature in sickle-cell patients.

The severity varies depending on the degree of haemolysis and erythropoietic activity.

51
Q

Why are sickle cell patients more at risk of infections?

A

Functional asplenia due to recurrent splenic infarctions increases susceptibility to encapsulated bacterial infections, such as Streptococcus pneumoniae and Haemophilus influenzae.

52
Q

Why are sickle cell patients at risk of leg ulcers?

A

Chronic venous insufficiency resulting from vaso-occlusion can lead to non-healing leg ulcers, predominantly around the medial malleoli.

53
Q

What are some possible differentials for sickle cell?

A
  • Thalassaemia
  • Autoimmune haemolytic anaemia
  • Hereditary spherocytosis
  • G6PD deficiency
54
Q

What investigation is required for diagnosis of sickle cell?

A

haemoglobin electrophoresis

55
Q

Management of a patient with SCA generally involves preventative measures and specific therapeutic interventions depending on the acute complication.

What triggers of crises should be avoided?

A
  • Cold temperatures
  • Dehydration
  • Exhaustion: may lead to lactic acidosis
  • Alcohol: may cause dehydration
  • Smoking: may cause the acute sickle chest syndrome
56
Q

How are infections prevented in sickle cell?

A

Oral penicillin prophylaxis is recommended until at least age five but is often continued life-long.

Vaccinations: regular childhood vaccinations plus vaccinations against meningococcus, pneumococcus, hepatitis B and influenza.

57
Q

How is severe anaemia prevented in sickle cell?

A

Folic acid supplementation

58
Q

How can sickle cell cause priapism?

A

Obstruction of venous outflow from the corpora cavernosa by sickled cells may cause persistent penile erection accompanied by pain.

59
Q

Aspects of management in sickle cell?

A

1) Preventative management: lifestyle, folic acid & Abx

2) Regular medications:
- blood transfusion
- hydroxycarbamide
- bone marrow transplant

3) Management of acute complications

60
Q

What is Hydroxycarbamide?

A

A once daily medication that increases HbF production (and thus reduces the proportion of HbS in the blood).

61
Q

When is Hydroxycarbamide given in sickle celkl?

A

It is offered to all patients with sickle cell anaemia from the age of 9 months old onwards (unless pregnant).

62
Q

What is a complication of regular blood transfusions in sickle cell?

A

Iron overload –> consider for iron chelation therapy.

63
Q
A
64
Q

What will haemoglobin electrophoresis reveal in sickle cell?

A

Presence of HbS as well as absent or decreased HbA levels.

65
Q

What are some complications of sickle cell to monitor for?

A

1) Stroke –> get head CT

2) Acute chest syndrome –> get CXR

3) Avascular necrosis of femoral head –> get XR or MRI of hips

4) Recurrent or severe infections due to functional asplenia

5) Dactylitis

6) Priapism

7) Gallstones

8) Retinopathy

9) Leg ulcers –> get a Doppler

66
Q

What does an XR show in avascular necrosis of the femoral head?

A

Sclerosis or flattened or collapsed femoral head

67
Q

What is dactylitis?

A

A condition in which acute vaso-occlusion of the fingers and toes leads to redness, swelling and pain (‘sausage digits’).

68
Q

What type of gallstones are seen in sickle cell?

A

Pigmented gallstones.

This is due to chronic red blood cell destruction leading to persistently elevated unconjugated bilirubin levels in sickle cell.

69
Q

How may retinopathy present in sickle cell?

A
  • Impaired vision
  • Decreased visual acuity
  • Restricted visual fields
  • Fundoscopy –> proliferative changes, neovascularisation, and vitreous hemorrhage
70
Q
A

Yr 4 - Paediatrics (78 decks)

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