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Paeds BPT Written Exam > Haematology > Flashcards

Haematology Flashcards

1
Q

What is Kostmann syndrome?

A

Severe congenital neutropenia
- Rare AR disorder
- Mutations: many, incl ELA2 and HAX1
- ANC <2 +/- monocytosis +/- eosinophilia
- Children are at risk of severe bacterial infection and early death
- Management
* G-CSF
BMT is curative!

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2
Q

Congenital neutropenia syndrome similar to CF?

A

Scwachman-Diamond Syndrome!
- Presentation
* FTT
* Steatorrhoea due to pancreatic insufficiency
* Recurrent infections
* Neutropenia, then anaemia and thrombocytopenia later
* Metaphyseal dysostoses

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3
Q

What is Wiskott-Aldrich syndrome?

A
  • Rare X-linked disorder characterised by severe thrombocytopenia and uniformly SMALL platelets
  • Presentation
    • Male, often presenting in neonatal period with thrombocytopenia
    • Eczema
    • Immunodeficiency
      Risk of lymphoma in later life
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4
Q

Causes of prolonged APTT?

A

Causes that correct on mixing studies:
1. Factor deficiency (8, 9, 11, 12)
2. VWD with low factor 8

Causes not corrected on mixing studies
3. Heparin contamination
4. Lupus anticoagulant (note this doesn’t cause bleeding)
5. Acquired factor 8 inhibitor

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5
Q

Causes of prolonged PT (with normal APTT)?

A

PT assess the extrinsic and common pathways

  • Congenital or acquired factor 7 deficiency
  • Mild liver disease
  • Mild vit K deficiency
  • Therapeutic warfarin
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6
Q

Causes of prolonged PT and aPTT?

A
  • DIC
  • Liver disease
  • Vitamin K deficiency
  • Congenital factor 1, 2, 5 or 10 deficiency
  • Supratherapeutic warfarin
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7
Q

What is Bernard Soulier syndrome?

A

An AR condition with mild thrombocytopenia and giant, abnormal platelets that do not aggregate. Absent GP1b -> defective platelet: vWF adhesion

Presents with mucocutaneous bleeding in infancy

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8
Q

What is Glanzmann Thrombasthenia?

A

An AR platelet surface receptor disorder of GPIIb/IIIa -> defective platelet: platelet aggregation

Presents with mucocutaneous bleeding in infancy

Often normal platelet count + size

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9
Q

MOA of Emucizumab?

A

New drug for Haemophilia A

MOA: Binds to factor IXa and factor X, mediating the activation of factor X
This is normally the role of factor VIII which is deficient in haemophilia A.

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10
Q

What does FFP contain?

A

Contains ALL coagulation factors at the same concentration as present in plasma. Also contains fibrinogen

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11
Q

Indications for FFP?

A

Deficiency of clotting factors with bleeding or risk of bleeding e.g
- Replacement of a single coagulation factor or protein deficiency if no factor specific concentrate is availabe (eg factor V, severe protein S deficiency)
- Prevention of dilution coagulopathy in setting of massive transfusion
- DIC

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12
Q

What does cryoprecipitate contain?

A

Contains most of the original factor 8, VWF, fibrinogen, factor 9 and fibronectin from FFP

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13
Q

Features of dyskeratosis congenital

A

Inherited BM failure syndrome with mucocutaneous features and cancer predisposition. Caused by impaired telomere maintenance -> short telomeres

Triad of reticular skin hypopigmentation, nail dystrophy, and oral leukoplakia

At risk of lung and liver fibrosis and
Cancer predisposition, most commonly head and neck cancer

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14
Q

Features of Fanconi anaemia

A

Inherited bone marrow failure syndrome

Skin hypo/hyperpigmentation/ CALMs (most common)
Short stature
UL abnormalities- hypo plastic or absent thumbs + radii
Hypogonadal + genital changes
Kidney abnormalities (ectopic, pelvis or horseshoe kidney)
Conductive hearing loss
CHD

Many meet criteria for VACTERL

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15
Q

Mechanism of clot breakdown?

A

initiated by tissue plasminogen activator (tPA) which is activated by protein C
tPA catalyses the conversion of plasminogen to plasmin which breaks down fibrin and fibrinogen and desolves the clot

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16
Q

What does aPTT measure?

A

assesses function on common and intrinsic pathway (factors 12, 11, 9, 8)

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17
Q

What does prothrombin time (PT) measure?

A

Assesses function of common + extrinsic pathway (factor 7)

“7 Pets”

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18
Q

What does thrombin time measure?

A

Measures the time it takes to convert fibrinogen -> fibrin

Will be prolonged with:
- decreased or defective fibrinogen
- presence of heparin or heparin-like anticoagulants
- elevated fibrin degradation products

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19
Q

Causes of small platelets (microthrombocytes)?

A

Wiskott Aldrich Syndrome (X-linked condition associated with severe thrombocytopenia, eczema, immunodeficiency)

Impaired platelet production in the BM (Eg due to aplastic anaemia, bone marrow infiltration, chemo, ionising radiation)

20
Q

Causes of large platelets (mega thrombocytes)?

A

Bernard Soulier syndrome
ITP
DIC
Thrombocytic microangiopathies
MYH19 related disorders (mutations in the gene for non muscle myosin heavy chain 2a)

Normally have <5% large platelets. Increased large platelets seen with high platelet turnover

21
Q

Features of Thrombocytopenia-Absent Radius (TAR) syndrome?

A

AR condition, presents with bleeding in neonate
- Thrombocytopenia (often <30), risk of IC bleeding. Can be exacerbated by infection and CMPA
- No radii but normal thumbs (unlike Fanconi anaemia)

Can also have hypo plastic carpals, syndactyly, hip dysplasia, femoral and/or tibial torsion
Dysmorphism: hypertelorism, broad forehead, low set ears
- CHD (30-35%): ASD, VSD or TOF

22
Q

Management of ITP

A
  1. Steroids
  2. IVIG - rapid onset (24hrs)
  3. Anti-D (only used if Rh + due to risk of haemolytic)
  4. Rituximab (anti-CD20) or elthrombopag (thrombopoeitin receptor agonist - stimulates thrombopoiesis)
23
Q

Pathophys of Thrombotic Thrombocytopenic Purpura?

A

ADAMTS-13 protease deficiency (AR) or destruction (autoimmune) -> lack of cleavage of vWF multimers. VWF circulate, stimulating microvascular platelet thrombi

24
Q

Management of TTP?

A

Plasma exchange
Steroids
Rituximab

25
Q

How does NAIT occur?

A

Mother develops anti-platelets antibodies against paternally-derived fetal platelet antigens (most commonly human platelet antigen/ HPA-1A) -> destruction of platelets and severe neonatal thrombocytopenia (self resolves after ~2/52)

26
Q

How does neonatal AUTOimmune thrombocytopenia differ from NAIT? (ALLOimmune)

A

Caused by maternal autoantibodies that react with both maternal and fetal platelets, these autoantibodies develop in setting of maternal thrombocytopenia or splenectomy
Only 10-25% of infants develop severe thrombocytopenia (it is more commonly mild)

27
Q

Management of neonatal autoimmune and alloimmune thrombocytopenia?

A

If severe thrombocytopenia or bleeding, give platelet transfusion and IVIg, otherwise monitor

28
Q

Difference between type 1, 2 and 3 von Willebrands disease?

A

Type 1 = reduced vWF antigen (quantitative defect)
Type 2= functional defect (qualitative defect)
vWF activity: vWF antigen <0.7
Type 3= undetectable vWF and consequently low factor 8 levels (it is a carrier of factor 8)

29
Q

Management of vWD

A
  1. Desmopressin (causes release of stored vWF and factor 8 from endothelial cells)
  2. Biostate (vWF and factor 8 concentrate)
  3. TXA (antifibrinolytic)
30
Q

What does von Willebrand factor do?

A
  1. Promotes platelet aggregation to exposed subendothelial surface and to other platelets
  2. Carrier protein for factor 8 in the blood
31
Q

Mechanism of action of aspirin?

A

Irreversibly inhibits COX -> prevents conversion of arachidonic acid to thromboxane A2 and therefore altering function of the platelet for its whole lifespan

32
Q

What % of factor activity do you have in mild, mod and severe haemophilia?

A

Mild: 6-40%
Moderate: 1-5%
Severe: <1%

33
Q

What is cryoprecipitate used for?

A

Cryoprecipitate contains fibrinogen, factor 8 and vWF.
Used for replacement of fibrinogen eg in DIC, trauma, congenital fibrinogen disorder

May also be used for vWF or haemophilia A

34
Q

Risk factors for vitamin K deficiency bleeding

A
  • No Vit K given
  • Antibiotics
  • GI malabsorption
  • Maternal warfarin or phenobarbital use
  • severe liver disease (as the vit-K dependent factors are synthesised in the liver)
35
Q

What is factor V Leiden

A

Factor 5 resistance to protein C, (a naturally occurring anti-coagulant which normally cleaves factor 5a making it inactive) so factor 5 remains in its active (procoagulant) form

36
Q

What is a chromosomal breakage analysis used for?

A

Diagnosis of Fanconi anaemia

37
Q

What would you expect on bloods in transient erythroblastopenia of childhood (TEC)?

A

Usually occurs in a child aged 1-3yrs
- Normocytic anaemia
- Low reticulocytes
- Normal HbF and erythrocyte adenosine deaminase (ADA), unlike DBA
- 20% have a mild neutropenia

38
Q

What would you expect on bloods in Diamond Blackfan Anaemia

A

Congenital red cell aplasia
- Macrocytic anaemia with low retics
- Elevated erythrocyte adenosine deaminase (ADA) activity - helps distinguish from TEC
- Elevated HbF

39
Q

What age is the usual physiological Hb nadir?

A

8-12 weeks (per Nelsons)

40
Q

Management of iron overload

A

Dexferoxamine (iron chelator)

AEs include ototoxicity, retinal changes, bone dysplasia

41
Q

What would you expect on blood film with G6PD Deficiency?

A

Heinz bodies (precipitated Hb)
Bite cells and blister cells

42
Q

Inheritence pattern of vWD?

A

Autosomal dominant (except type 3 which is autosomal recessive)

43
Q

How does cyclical neutropenia present?

A

Neutropenia at REGULAR intervals (usually every 21 +/-3 days) and lasts 3-7 days
- associated fever
- apthous ulcers
- stomatitis
- pharyngitis + cervical lymphadenopathy

44
Q

What is the underlying pathophysiology of Diamond Blackfan anaemia?

A

It is a ribosompathy - caused by a gene mutation for a protein of the 40S or 60S ribosomal subunit

45
Q

What condition are giant platelets and Dohle bodies associated with?

A

MYH9 -related disorders
(autosomal dominant cause of thrombocytopenia, SNHL and cataracts)

46
Q
A

Paeds BPT Written Exam (18 decks)

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