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Paediatrics > Haematology > Flashcards

Haematology Flashcards

1
Q

Describe how haemoglobin changes during life. Why does this matter?

A
  • Fetal development: HbF is main form. 2 alpha, 2 gamma. Higher affinity for O2.
  • First year: HbF replaced by HbA (2 alpha, 2 beta) and HbA2 (2 alpha, 2 delta)

Diseases affecting beta globin chains (SCA, B thal) will not be obvious at birth, but will present during the first year of life as Hb switches

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2
Q

How does the FBC differ in neonates?

A
  • Hb high -> quick fall
  • WCC high
  • Iron stores low (in preterm)
  • Plts normal
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3
Q

Define anaemia in children

A
  • Neonates: <140 g/L
  • 1 month-12 months: <100 g/L
  • 1-12 years: <110 g/L
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4
Q

Name some categories and causes of anaemia in children

A

Decreased production: bone marrow failure, Fe deficiency, folate deficiency, chronic inflammation, red cell aplasia
Increased breakdown: haemolytic anaemia eg. SCA, spherocytosis, G6PD deficiency, thalassaemia, HUS
Loss: haemorrhage, bleeding disorders causing chronic bleeding

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5
Q

What are some causes of Fe deficiency in childhood? What are the features (clinical and haem)?

A

-Poor diet eg. milk only
-Malabsorption
-Blood loss
Clinical features: pallor, fatigue, SOB, failure to thrive, pica
Haematological features: low Hb, low MCV, low ferritin

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6
Q

When does anaemia become symptomatic in children?

A

Not until Hb <60-70 g/L eg. VERY low

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7
Q

Describe the management of iron deficiency in children

A
  • Conservative: dietary advice eg. dark leafy greens, red meat. Take with vitamin C eg tomatoes
  • Medical: supplementation (oral ferrous sulphate). Can take with food to minimise GI upset.

-Monitor response to treatment: FBC 2-4 weeks after starting treatment -> again 2-4 months later. Continue for 3 months when normal to maintain stores.

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8
Q

Name some causes of red cell aplasia in children

A
  • Parvovirus B19: in children with haemoglobinopathy
  • Diamond-Blackfan anaemia: congenital
  • Transient erythroblastopenia of childhood: viral trigger
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9
Q

How would you approach diagnosing a child with anaemia?

A
  • Film: haemolysis? eg. SCA, spherocytosis, G6PDD, etc
  • Haematinics: Fe/folate/B12 deficiency
  • Reticulocyte count: low in aplasia, ^ in haemolysis
  • DAT test: autoimmune cause
  • Bilirubin, haptoglobin: ^ in haemolysis
  • Dye binding test, osmotic fragility test
  • Bone marrow biopsy
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10
Q

Name some causes of haemolytic anaemia in children

A 
Neonates: Rh disease, ABO incompatibility
Mostly due to intrinsic abnormalities:
-G6PD deficiency
-Hereditary spherocytosis
-Sickle cell
-Thalassaemia
Immune-mediated is UNCOMMON
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11
Q

Describe the pathophysiology of hereditary spherocytosis

A

Autosomal dominant condition
Mutation in membrane proteins eg. spectrin/ankyrin
-> membrane defects -> haemolysis in spleen

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12
Q

What tests can be used to diagnose hereditary spherocytosis?

A

FBC and blood film
Dye binding test
Osmotic fragility test

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13
Q

What is the management of hereditary spherocytosis?

A

Supportive care
Daily folic acid supplements (to support turnover)
Daily pneumococcal prophylaxis (oral penicillin)

Splenectomy if needed
RBC transfusion if severely anaemic eg. parvovirus

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14
Q

Describe the pathophysiology of G6PD deficiency. How is it diagnosed?

A

X-linked defect in enzyme in the pentose phosphate shuttle
-> if oxidative damage, not fixed
-> destruction
Causes of oxidative damage include: infection, antimalarials (eg quinines), sulfonamides, quinolones, nitrofurantoin, naphthalene, fava beans
Diagnosis: between episodes: G6PD activity

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15
Q

Describe the pathophysiology of sickle cell disease

A

AR point mutation in codon 6 of the beta globin gene
GAG -> GTG means glutamine -> valine
Causes abnormal beta globin (HbS)
Sickling of cells when not oxygenated -> occlusion -> haemolysis, painful crises, strokes, etc

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16
Q

What are the different types of sickle cell disease? Which types have HbA?

A
  • Sickle cell anaemia: HbSS -> no HbA
  • HbSC: one HbS, one HbC (different mut) -> no HbA
  • Sickle beta thal: one HbS, one beta thal -> no HbA
  • Sickle cell trait: HbS (1/2 beta chains affected)
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17
Q

What can trigger a sickle cell crisis?

A

Hypoxia
Cold
Dehydration
Infection

18
Q

Name some features of sickle cell anaemia

A
  • Anaemia: fatigue, pallor
  • Infection: increased risk with encapsulated bacteria
  • Painful crises: hand-foot syndrome (dactylitis), acute chest syndrome
  • Splenic sequestration -> hyposplenism
  • Aplastic crisis: infection with parvovirus B19
  • Priapism
  • Long term: poor growth, heart failure, neurological damage/stroke
19
Q

Describe the management of sickle cell anaemia

A
  • Prevention: lifestyle (eg. stay warm, hydrated). High dose folic acid, vaccination, daily penicillin. Malarial prophylaxis if travelling
  • Medical management: hydroxycarbamide (^ HbF), hydroxyurea, splenectomy, BMT.
  • Acute crises: admit. Supportive eg. hydrate, warm, oxygenate. Pain relief (opioid + anti-emetic and laxative) Treat infection. Exchange transfusion if acute chest/priapism. Blood transfusion if severely anaemic/aplastic crisis.
20
Q

Describe the pathophysiology of thalassaemias + types.

A

Alpha thal: defect in alpha globin chain. 4 genes.

  • 2-3/4 functional: asymp/mild anaemia similar to Fe deficiency
  • 1/4 functional: HbH. Mild-mod anaemia. May need transfusions
  • 0 functional: Hb Barts, causes fetal hydrops. Fatal/ requires intrauterine transfusion.

Beta thal: defect in beta globin. 2 genes.

  • Trait: asymp/mild anaemia.
  • Intermedia: mild-mod anaemia
  • Major: no HbA. Severe anaemia from infancy, requiring regular transfusions/BMT.
21
Q

How does thalassaemia present?

A
  • Anaemia (microcytic)
  • Jaundice
  • Extramedullary haematopoiesis: skull bossing, maxillary overgrowth, hepatomegaly
  • Splenomegaly
22
Q

What are some effects of repeated blood transfusions? What is the treatment?

A

-Iron deposition: pancreatic insufficiency, cardiomyopathy, cirrhosis, hyperpigmentation
-Risk of infection, allo-antibody formation
Important to do iron chelation therapy for children with repeated transfusions eg. desferrioxamine

23
Q

How is thalassaemia diagnosed?

A
  • Microcytic hypochromic anaemia
  • Normal/high reticulocytes
  • Hb high performance liquid chromatography (HPLC) or Hb electrophoresis (raised HbA2)
24
Q

How is sickle cell anaemia diagnosed?

A
  • Screening eg. Guthrie
  • Microcytic hypochromic anaemia
  • Normal/high reticulocytes
  • Blood film
  • Hb electrophoresis/HPLC
25
Q

Name some causes of bone marrow failure in children. How does it present?

A

-Idiopathic
-Drugs: sulphonamides, chemotherapy
-Infection: hepatitis
Presents with deficiency in all 3 lineages:
-Anaemia with low reticulocytes
-Thrombocytopenia with bleeding, bruising
-Neutropenia with infections

26
Q

Name some different bleeding disorders and the causes

A
  • Haemophilia A/B: deficiency in FVIII/FIX -> secondary haemostasis defect
  • vWD: deficiency in vWF -> primary haemostasis defect
  • Drugs eg. anticoagulants
  • Liver disease: deficiency in clotting factors
  • ITP, DIC
27
Q

Describe the pathophysiology of haemophilia. How does it present?

A
  • X linked recessive condition
  • Mutation in gene coding FVIII (A) or FIX (B)
  • Leads to defects in secondary haemostasis
  • Presents with: bruising, haemarthrosis, prolonged bleeding from larger wounds. Usually presents when children learn to walk/crawl
28
Q

Describe the management of haemophilias

A

Conservative: avoid contact sports, injuries. No IM injections. No aspirin/NSAIDs

Medical: MDT approach with paeds, ortho, physio

  • Acute bleeding: recombinant FVIII/FIX concentrate + antifibronolytics (TXA)
  • Give prophylactic doses if severe, or replacement therapy if low levels as needed
  • DDAVP can be used in mild Haem A to ^ vWF/FVIII
29
Q

Describe the pathophysiology of vWD. How does it present?

A

-Several types, include deficiency of vWF +/- FVIII
-Defective platelet plug formation
-Defect of primary haemostasis
Presents with: bruising, prolonged bleeding, bleeding from gums/mucous membranes.

30
Q

Describe the management of vWD

A

Conservative: avoid IM injections, NSAIDs/aspirin

  • Mild Type 1: DDAVP- stimulates vWF and FVIII
  • Severe: FVIII concentrate
31
Q

How would you investigate bleeding disorders?

A

Initial tests:

  • FBC and film
  • LFTs
  • Clotting screen: APTT, PT, fibrinogen
  • D dimer

Further testing:

  • FVIII and FIX levels
  • Bone marrow biopsy
  • Platelet function tests, vWF antigen, etc.
32
Q

Define thrombocytopenia. Name some causes

A

Platelets <150 x 10^9 /L

  • Malignancy: ALL
  • ITP
  • TTP
  • HUS
  • DIC
  • SLE
33
Q

What is the platelet count in vWD?

A

Usually normal

34
Q

Describe the pathophysiology of ITP

A
  • Most common cause of thrombocytopenia in kids
  • Usually 2-10 years, weeks after viral infection
  • IgG antibodies to platelets -> destruction
  • Increase in megakaryocytes in bone marrow
35
Q

How does ITP present? How is it diagnosed?

A
  • 1-2 weeks after viral infection -> thrombocytopenia eg. petechiae, purpura, bleeding from mucous membranes
  • Self-limiting, resolves in 6-8 weeks
  • No other blood cell dyscrasias, no clinical signs (hepatosplenomegaly, lymphadenopathy)
  • Dx: rule out other causes. FBC and film, clotting, LFTs, D dimer, HIV serology in high risk, SLE antibodies, etc. Consider bone marrow biopsy if not normal findings to rule out leukemia
36
Q

Describe the management of ITP

A
  • Life threatening or severe bleeding: platelet transfusion, IVIG, steroids
  • Mild bleeding: manage at home, safety net
  • Moderate bleeding: steroids, IVIG
37
Q

What is DIC? When does it occur? How is it diagnosed?

A

Disseminated intravascular coagulation: occurs when there is increased consumption of platelets and clotting factors -> lots of small thrombi -> bleeding due to overconsumption
Can occur in sepsis, shock, trauma, burns
Usually have impairment in all clotting parameters eg. prolonged PT and APTT, low platelets, low fibrinogen, high D dimer

38
Q

What can cause thrombosis in children?

A

Uncommon, usually due to inherited thrombophilia
eg. Protein C/S deficiency, Factor V Leiden
Also DIC, malignancy

39
Q

Name some causes of bruising in children

A 
Bruising:
-Accidental injury
-NAI/abuse
-Malignancy
-Haemophilia
Purpura/petechiae: 
-vWD
-HSP
-Meningococcal sepsis
-ITP
40
Q

A mother brings in her 4 year old son concerned over some new bruising. What are some differentials, and what do you want to know?

A
  • DDx: accidental injury, NAI, malignancy, haemophilia, sepsis, ITP, HUS, HSP, etc
  • Onset, progression
  • Describe bruising pattern, size (bruising or purpura), swollen joints
  • Any explanation? Trauma? Rough playing?
  • General health: weight loss, fatigue, fever, anorexia, swellings
  • Anaemia screen: SOB, pallor
  • Infections
  • PMH including bleeding problems especially after vaccination*, DHx, allergies
  • Immunisations, development screen
  • FHx of bleeding disorders
  • Social: changes at home, new people around, healthy relationships, DV, alcohol/drugs, social worker

Paediatrics (13 decks)

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