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Paeds: Gastro and Growth > Anaemia > Flashcards

Anaemia Flashcards

1
Q

What is anaemia?

A

Hb below the normal range

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2
Q

What is the limit for anaemia in neonates?

A

Hb < 140g/L

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3
Q

What is the limit for anaemia in children 1 month to 12 months?

A

Hb <100g/L

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4
Q

What is the limit for anaemia in children 1 year to 12 years?

A

< 110 g/L

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5
Q

What are the 3 mechanisms which can be causes of anaemia?

A
  1. Reduced red cell production - either due to ineffective erythropoiesis (e.g. iron deficiency, the most common cause of anaemia) or due to red cell aplasia
  2. Increased red cell destruction (haemolysis)
  3. Blood loss - relatively uncommon cause in children
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6
Q

What is an example of when all 3 causes of anaemia (increased destruction, reduced production, loss) contribute?

A

anaemia of prematurity

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7
Q

What are 2 broad causes of impaired red cell production?

A
  1. Red cell aplasia
  2. Ineffective erythropoiesis
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8
Q

What are 4 causes of red cell aplasia?

A
  1. Parvovirus B19 infection
  2. Diamond-Blackfan anaemia (congenital red cell aplasia)
  3. Transient erythroblastopenia of childhood
  4. Rarities: Fanconi anaemia, aplastic anaemia, leukaemia
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9
Q

What are 5 causes of ineffective erythropoiesis?

A
  1. Iron deficiency
  2. Folic acid deficiency
  3. Chronic inflammation (e.g. juvenile idiopathic arthritis)
  4. Rarities: meylodysplasia, lead poisoning
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10
Q

What are 4 causes of increased red cell destruction (haemolysis)?

A
  1. Red cell membrane disorders e.g. hereditary spherocytosis
  2. Red cell enzyme disorders: G6PD deficiency
  3. Haemoglobinopathies: thalassaemias, sickle cell disease
  4. Immune: haemolytic disease of the newborn, autoimmne haemolytic anaemia
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11
Q

What are 3 causes of blood loss that can lead to anaemia in children?

A
  1. Feto-maternal bleeding
  2. Chronic gastrointestinal blood loss - Meckel diverticulum
  3. Inherited bleeding disorrders e.g. vWD
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12
Q

What is a good diagnostic approach to a cause of anaemia in children?

A
  • Reticulocytes low or high?
    • If low - red cell production likely affected: red cell aplasia
  • If normal or high: is bilirubin raised?
    • If bilirubin raised: haemolysis
    • If bilirubin normal: blood loss of ineffective erythropoiesis
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13
Q

How can you differentiate between hereditary spherocytosis / sickle cell disease / beta-thalassaemia as causes of haemolysis?

A

blood film + Hb HPLC: high performance liquid chromatography

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14
Q

What will blood film + Hb HPLC show in hereditary spherocytosis?

A

blood film will show spherocytes

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15
Q

What will blood film + Hb HPLC show in sickle cell disease?

A

blood film will show sickle cells and target cells

Hb HPLC will show HbS and no HbA

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16
Q

What will blood film + Hb HPLC show in thalassaemia?

A

hypochromic/microcytic red cells in thalassaemia

in beta thalassaemia major, HPLC will show only HbF present; in beta thalassaemia trait, main abnormality is increased HbA2

in alpha thalassaemia trait, Hb HPLC is normal

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17
Q

What is meant by ineffective erythropoiesis?

A

red cell production occurs at a normal or increased rate but diffrentiation and survival of red cells is defective (e.g. iron deficiency)

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18
Q

What is red cell aplasia?

A

complete absence of red cell production

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19
Q

What are 2 diagnostic clues to ineffective erythropoiesis?

A
  1. Normal reticulocyte count
  2. Abnormal mean cell volume (MCV) of the red cells: low in iron deficiency and raised in folic acid deficiency
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20
Q

What are the 3 main causes of iron deficiency in children?

A
  1. Inadequate intake
  2. Malabsorption
  3. Blood loss
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21
Q

Why is inadequate intake of iron common in infants?

A

additional iron is required for the increase in blood volume

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22
Q

What is the iro requirement of a 1 year old infant?

A

8mg/ day

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23
Q

What are 4 sources of iron for a child and how much do they provide?

A
  1. Breastmilk - low iron content but 50% of iron absorbed
  2. Infant formula - supplemented with adequates amount of iron
  3. Cow’s milk - higher iron content than breastmilk but only 10% absorbed
  4. Solids introduced at weaning e.g. cereals (cereals supplemented with iron but only 1% absorbed)
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24
Q

What are 2 causes of inadequate intake of iron in children?

A
  1. Delay in introduction of mixed feeding beyond 6 months of age
  2. Diet with insufficient iron rich foots, especially if it contains large amount of cow’s milk
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25
Q

How can the absorption of iron be increased?

A

when eaten with food rich in vitamin C (fresh fruit and vegetables)

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26
Q

What inhibits the absorption of iron?

A

tannin in tea

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27
Q

What are 9 food sources of iron?

A
  1. Red meat - beef, lamb
  2. Liver, kidney
  3. Oily fish - pilchards, sardines
  4. Pulses, beans and peas
  5. Fortified breakfast cereals with added vitamin C
  6. Wholemeal products
  7. Dark green veg - broccoli, spinach
  8. Dried fruit - raisins, sultanas
  9. Nuts and seeds
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28
Q

What are 3 foods to avoid in excess in toddlers?

A
  1. Cow’s milk
  2. Tea: tannin, inhibits iron uptake
  3. High-fibre foods: phytates inhibit iron absorption
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29
Q

When do children and infants become symptomatic for iron deficiency?

A

if drops below 60-70 g/L

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30
Q

What are 5 clinical features of iron deficiency?

A
  1. Tiring easily
  2. Feed more slowly
  3. Pallor of conjunctivae, tongue or palmar creases
  4. Pica - eating soil, chalk, gravel, foam rubber
  5. Detrimental behaviour and intellectual function
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31
Q

If you suspect iron deficiency what are 2 thigs to always ask about?

A
  1. Blood loss
  2. Symptoms suggesting malabsorption
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32
Q

What are the findings on investigation in iron deficiency anaemia?

A
  1. Microcytic, hypochromic anaemia (low MCV and mean cell haemoglobin, MCH)
  2. Low serum ferritin
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33
Q

What are the 3 main causes of microcytic anaemia in children?

A
  1. Iron deficiency anaemia
  2. Beta thalassaemia trait (usually Asian, Arabic or Mediterranean origin)
  3. Anaemia of chronic disease
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34
Q

What can be said about anaemia and alpha thalassaemia trait?

A

have a microcytic/hypochromic blood picture but mostly not anaemic

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35
Q

From what region are most people with alpha thalassaemia trait?

A

African or Far Eastern origin

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36
Q

What is the management of iron deficiency anaemia?

A
  • For most: dietary advice and supplementation with oral iron
  • Investigation for malabsorption e.g. coeliac disease or chronic blood loss (e.g. due to Meckel diverticulum) if history or exam suggests non-dietary cause or failure to respond to therapy in compliant patients
  • blood transfusion should never be necessary for dietary iron deficiency - even if gradually declined to 20-30 g/L
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37
Q

What are 2 forms of oral iron supplementation best tolerated in children?

A
  1. Sutron (sodium iron edetate)
  2. Niferex (polysaccharide iron complex)
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38
Q

For how long should iron supplementation be continued?

A

until Hb normal and thne for minimum of 3 further months (to replenish the iron stores)

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39
Q

How much should iron rise by with good compliance with oral supplementation?

A

10g/L per week

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40
Q

How can iron deficiency with normal Hb present?

A

biochemical evidence of iron deficiency e.g. low serum ferritin, but have not yet develop anaemia

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41
Q

What is the suggested management of treatment of iron deficiency with normal Hb?

A

provide dietary advice to increase oral iron and its absorption, offer option of additional treatment with oral iron supplements

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42
Q

What are 3 main causes of red cell aplasia in children?

A
  1. Congenital red cell aplasia (Diamond-Blackfan anaemia)
  2. Transient erythroblastopenia of childhood
  3. Parvovirus B19 infection (only causes red cell aplasia in children with inherited haemolytic anaemis and not in healthy children)
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43
Q

When can parvovirus B19 cause red cell aplasia?

A

children with inherited haemolytic anaemias and not in healthy children

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44
Q

What are 4 diagnostic clues to red cell aplasia?

A
  1. Low reticulocyte count despite low Hb
  2. normal bilirubin
  3. negative direct antiblobulin test (Coombs test)
  4. absent red cell precursors on bone marrow examination
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45
Q

What proportion of cases of Diamond-Blackfan anaemia have a family history?

A

20% (80% are sporadic)

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46
Q

What is sometimes the genetic cause of Diamond-Blackfan anaemia?

A

gene mutation in ribosomal protein (RPS) genes are implicated in some cases

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47
Q

What is the typical age of presentation of Diamond-Blackfan anaemia?

A

2-3 months usually, 25% present at birth

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48
Q

What are 2 features of presentation of Diamond-Blackfan anaemia?

A
  1. Symptoms of anaemia
  2. Some have other congenital anomalies such as short stature or abnormal thumbs
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49
Q

What is the treatment of Diamond-Blackfan anaemia? 3 aspects

A
  • oral steroids
  • monthly red blood cell transfusions if steroid unresponsive
  • some also offered stem cell transplantation
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50
Q

What causes transient erythroblastopenia of childhood?

A

usually triggered by viral infections

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51
Q

What are 3 key differencea between transient erythroblastopenia of childhood (TEC) and Diamond-Blackfan anaemia?

A
  • TEC always recovers, usually within several weeks
  • no family history or RPS gene mutations
  • no congenital anomalies
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52
Q

What causes haemolytic anaemia in generally?

A

reduced red cell lifespan due to increased red cell destruction in the circulation (intravascular haemolysis) or liver or spleen (extravascular haemolysis)

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53
Q

What is the normal lifespan of a red cell?

A

120 days

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54
Q

How long might red cell lifespan be in haemolysis?

A

a few days

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55
Q

When does haemolysis lead to anaemia?

A

bone marrow production can increase about 8 fold, so only becomes anaemia when bone marrow no longer able to compensate for premature destruction of red cells

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56
Q

What are 3 main causes of haemolysis in children?

A
  1. Red cell membrane disorders e..g hereditary spherocytosis
  2. Haemoglobinopathies (abnormal haemoglobins e.g. beta-thalassaemia major, sickle cell disease)
  3. Red cell enzyme disorders e.g. G6PD
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57
Q

What are 4 consequences of haemolysis from increased ed cell breakdown?

A
  1. Anaemia
  2. Hepatomegaly and splenomegaly
  3. Increased blood levels of unconjugated bilirubin
  4. Excess urinary urobilinogen
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58
Q

What are 5 diagnostic clues to haemolysis?

A
  1. Raised reticulocyte count (on blood film this is called ‘polychromasia’ as the reticulocytes have charactertic lilac colour on blood film
  2. Unconjugated bilirubinaemia and icnreased urinary urobilinogen
  3. Abnormal appearance of the red cells on a blood film (e.g. spherocytes, sickle shaped or very hypochromic)
  4. positive direct antiglobulin test (only if an immune cause, as this test identifies antibody-coated red blood cells)
  5. Increased red blood cell precursors in the bone marrow
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59
Q

What ethnicity is usually affected by hereditary spherocytosis?

A

Caucasians

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60
Q

What proportion of hereditary spherocytosis is inherited and what is the inheritance pattern?

A

75%; autosomal dominant

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61
Q

What causes hereditary spherocytosis?

A
  • mutations in genes for proteins of the red cell membrane (mainly spectrin, ankyri, or band 3)
  • causes red cell to lose part of its membrane when it passes through the spleen
  • reduction in surface-to-volume ratio causes cells to become spheroidal, making them less deformable than normal red blood cells and leads to their destruction in microvasculature of the spleen
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62
Q

What are 6 possible clinical features of hereditary spherocytosis?

A
  1. May be asymptomatic (variable)
  2. Jaundice - may be intermittent
  3. Anaemia - may fall during infections
  4. Mild to moderate splenomegaly
  5. Aplastic crisis - uncommon, transient (2-4 weeks), caused by parvovirus B19 infection
  6. Gallstones - due to increased bilirubin excretion
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63
Q

What can cause aplastic crisis in hereditary spherocytosis and how long does it last for?

A

parvovirus B19; 2-4 weeks (transient)

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64
Q

What is the diagnosis of hereditary spherocytosis based on?

A
  • blood film usually diagnostic
  • more specific tests available (e.g. dye binding assay or osmotic fragility), although seldom required
  • Autoimmune haemolytic anaemia is also associated with spherocytes but this can be excluded by a positive direct antibody test and the absence of a family history of hereditary spherocytosis
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65
Q

What is the management of hereditary spherocytosis?

A
  • mild: oral folic acid only
  • splenectomy beneficial, only if poor growth or troublesome symptoms of anaemia (e.g. severe tiredness, loss of vigour)
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66
Q

At what age is splenectomy usually performed for hereditary spherocytosis and why?

A

after age 7 years, risks of postsplenectomy sepsis

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67
Q

3 things that must be done prior to splenectomy for hereditary spherocytosis, and what else is advised?

A
  1. vaccinated against Haemophilus influenzae (Hib)
  2. meningitis C, &
  3. Streptococcus pneumoniae

+ lifelong daily oral penicillin prophylaxis advised

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68
Q

What is the management of aplastic crisis from parvovieus B19 infection in hereditary spherocytosis?

A

one or two blood transfusions required over the 3-4 week period when no red blood cells are produced

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69
Q

What may be necessary to treat gallstones in hereditary spherocytosis?

A

cholecystectomy - if symptomatic

70
Q

In what regions does G6PD deficiency have a high prevalence?

A

Central Africa, Mediterranean, Middle East, Far East

71
Q

What is the pathophysiology of G6PD deficiency?

A
  • Red cells lacking G6PD are susceptible to oxidant-induced haemolysis (usually caused by certain drugs)
  • In Mediterranean, Middle Eastern, and Oriental populations, affected males have very low or absent enzyme activity in their red cells. Affected African Americans have 10–15% normal enzyme activity.
72
Q

What is the inheritance pattern of G6PD deficiency?

A
  • X-linked and therefore predominantly causes symptoms in males.
  • Females who are heterozygotes are usually clinically normal as they have about half the normal G6PD activity.
  • Females may be affected either if they are homozygous or, more commonly, when by chance more of the normal than the abnormal X chromosomes have been inactivated (extreme Lyonisation – the Lyon hypothesis is that, in every XX cell, one of the X chromosomes is inactivated and that this is random).
73
Q

What are 4 types of drugs which can cause haemolysis in children with G6PD deficiency?

A
  1. Antimalarians: primaguine, quinine, chloroquine
  2. Antibiotics: sulfonamides (including co-trimoxazole), quinolones (ciprofloxacin), nitrofurantoin
  3. Aspirin
  4. Chemicals: naphthalene (mothballs), divicine (fava beans aka broad beans)
74
Q

What are 2 ways that patients with G6PD deficiency may present?

A
  1. Neonatal jaundice in first 3 days of life
  2. Acute haemolysis
75
Q

What are 4 things that can precipitate acute haemolysis in patients with G6PD?

A
  1. Infection - most common
  2. Certain drugs
  3. Fava beans (broad beans, other types don’t cause)
  4. Naphthalene in mothballs
76
Q

How does haemolysis in G6PD deficiency present?

A

predominantly intravascular, presents with:

fever, malaise, abdominal pain, passage of dark urine

rapid drop in Hb over 24-48h

77
Q

How is a diagnosis of G6PD deficiency made?

A
  • measuring G6PD activity in red blood cells
    • During a haemolytic crisis, G6PD levels may be misleadingly elevated due to the higher enzyme concentration in reticulocytes - produced in increased numbers in response to the destruction of mature red cells.
    • A repeat assay is then required once the haemolytic episode is over to confirm the diagnosis.
78
Q

Why do you need to confirm a diagnosis of G6PD after a haemolytic episode?

A

During haemolytic crisis, G6PD levels may be misleadingly elevated due to higher enzyme concentration in reticulocytes - produced in increased numbers in response to the destruction of mature red cells.

79
Q

What is the management of G6PD deficiency?

A

give parents advice about signs of acute haemolysis (jaundice, pallor, dark urine)

give list of drugs, chemicals, and food to avoid

transfusions rarely required

80
Q

What are haemoglobinopathies?

A

red blood cell disorders which cause haemolytic anaemia because of reduced or absent production of HbA (α-thalassaemias and β-thalassaemias) or because of the production of an abnormal Hb (e.g. sickle cell disease).

81
Q

What causes alpha-thalassaemia?

A

caused by deletions (occasionally mutations) in the alpha-globin gene

82
Q

What causes beta thalassaemia and sickle cell disease?

A

caused by mutations in the beta-globin gene

83
Q

When do haemoglobinopathies affecting the beta-chain (beta thalassaemia and sicke cell disease) present and why?

A

6 months of age, as this is when most of the hbF present at birth has been replaced

84
Q

What is the inheritance of sickle cell disease?

A

autosomal recessive

85
Q

What is sickle cell disease?

A

HbS is inherited

HbS forms as a result of point mutatin in codon 6 of beta-globin gene, which causes a chang ein the amino acid encoded from glutamine to valine

86
Q

In which ethnic groups is sickle cell disease most common?

A

tropical Africa/Caribbean, also middle East

87
Q

What are the 3 main forms of sickle cell disease?

A
  1. Sickle cell anaemia (HbSS)
  2. HbSC disease (HbSC)
  3. Sickle beta-thalassaemia
88
Q

What causes sickle cell anaemia (HbSS)?

A

patients are homozygous for HbS - virtually all Hb is HbS

small amounts of HbF and no HbA because they have the sickle mutation in both beta-globin genes

89
Q

What causes HbSC disease (HbSC)?

A

affected children inherit HbS from one parent and HbC from the other parent (HbC is formed as a result of a different point mutation in β-globin), so they also have no HbA (like HbSS) because they have no normal β-globin genes.

90
Q

What causes sickle beta-thalassaemia?

A

affected children inherit HbS from one parent and β-thalassaemia trait from the other. They have no normal β-globin genes and most patients can make no HbA and therefore have similar symptoms to those with sickle cell anaemia.

91
Q

What is meant by a carrier / aka sickle trait?

A

inheritance of HbS from one parent and normal beta-globin gene from other parent, so is a carrier and 40% of their haemoglobin is HbS

don’t have sickle cell disease, are asymptomatic but can transmit to offspring

92
Q

What happens to blood cells in sickle cell disease that leads to clinical manifestations?

A
  • HbS polymerises within red blood cells forming rigid tubular spiral bodies which deform the red cells into a sickle shape
  • Sickled red cells have a reduced lifespan and may be trapped in the microcirculation, resulting in blood vessel occlusion (vaso-occlusion) and therefore ischaemia in an organ or bone.
93
Q

What are 3 things that can exacerbate the manifestations of sickle cell disease?

A

low oxygen tension, dehydration, and cold

94
Q

Which is the most severe form of sickle cell disease?

A

HbSS is the most severe form of the disease (sickle cell anaemia)

95
Q

What is one of the key things that determines severity of sickle cell disease?

A

amount of HbF

most patients with sickle cell disease have HbF levels of 1%, genetic variation means that some patients naturally produce more HbF (e.g. 10–15% of their Hb may be HbF)- results in a marked reduction in disease severity

research is being carried out into drugs which increase HbF

96
Q

What are 7 clinical manifestations of sickle cell disease?

A
  1. Anaemia
  2. Infection
  3. Painful crises
  4. Acute anaemia
  5. Priapism
  6. Splenomegaly
  7. Long-term problems
97
Q

Why are patients at increased risk of infection in sickle cell diseaes?

A

Hyposplenism secondary to chronic sickling and microinfarction in the spleen in infancy

98
Q

What type of infections are sickle cell disease patients at increased risk of?

A

encapsulated organisms e.g. pnemococci and Haemophilus influenzae

increased incidence of osteomyelitis caused by Salmonella and other organisms

99
Q

When is the risk of sepsis from infection in sickle cell disease greatest?

A

early childhood

100
Q

What causes painful crises in sickle cell disease?

A

vaso-occlusive crises causing pain affecting many organs

101
Q

What are 4 types of painful crises in sickle cell disease?

A
  1. Hand-foot syndrome: dactylitis in fingers and/or feet
  2. Bones of limbs and spine
  3. Acute chest syndrome
  4. Avascular necrosis of femorla heads
102
Q

What causes painful crises in sickle cell disease?

A

vaso-occlusive crises - abnormal red blood cells blocking vasculature

103
Q

What is the most serious type of painful crisis in sickle cell disease?

A

acute chest syndrome: can lead to severe hypoxia and need for mechanical ventilation and emergency transfusion

104
Q

What are 5 things that can precipitate acute vaso-occlusive crises in sickle cell disease?

A
  1. Cold
  2. Dehydration
  3. Excessive exercise or stres
  4. Hypoxia
  5. Infection
105
Q

What are 3 things that can cause acute anaemia in sickle cell disease?

A
  1. Haemolytic crises - infection
  2. Aplastic crises - parvovirus infection
  3. Sequestration crises - accumulation of sickled cells in spleen
106
Q

How might sequestration crises (causing acute anaemia) present in sickle cell disease? 3 features

A
  1. sudden splenic or hepatic enlargement
  2. abdominal pain
  3. circulatory collapse
107
Q

What is the treatment of priapism and why?

A

needs to be treated promptly with exchange transfusion as may lead to fibrosis of the copora cavernosa and subsequent erectile impotence

108
Q

In which age group of children is splenomegaly a common acute presentation in sickle cell disease?

A

young children (much less common in older children)

109
Q

What are 8 possible long-term problems of sickle cell disease?

A
  1. Short stature and delayed puberty
  2. Stroke and cognitive problems
  3. Adenotonsillar hypertrophy - causing sleep apnoea, nocturnal hypoxaemia
  4. Cardiac enlargement - chronic anaemia
  5. Heart failure - uncorrected anaemia
  6. Renal dysfunction
  7. Pigment gallstones
  8. Leg uclers
  9. Psychosocial problems - education and behaviour
110
Q

Why is adenotonsillar hypertrophy a problem in sickle cell disease?

A

can cause sleep apnoea syndrome leading to nocturnal hypoxaemia, which can cause vaso-occlusive crises and/or stroke

111
Q

What are 3 aspects of the treatment of sickle cell disease?

A
  1. Prevention of infection
  2. Treatment of acute crises
  3. Treatment of chronic problems
112
Q

What are 4 types of prophylaxis against infection in sickle cell disease?

A
  1. Pneumococcal vaccination
  2. Meningococcal vaccination
  3. Haemophilus influenzae type B vaccination
  4. Daily oral penicillin throughout childhood
113
Q

What is given daily to children with sickle-cell disease due to chronic haemolytic anaemia?

A

oral folic acid - increased demand due to chronic haemolytic anaemia

114
Q

What are 3 methods to prevent vaso-occlusive crises?

A
  1. Avoiding exposure to cold e.g. dresing warmly, keep warm after swimming/ playing outside
  2. Avoid dehydration e.g. give drinks especially before exercise
  3. Prevent excessive exercise or undue stress
115
Q

What are 4 aspects of the management of acute crises in sickle cell disease?

A
  1. Oral or IV analgesia according to need - may require opiates
  2. Good hydration (oral or IV as required)
  3. Treat infection with antibiotics
  4. Oxygen should be given if sats reduced
  5. Exchange transfusion for acute chest syndrome, stroke, priapism
116
Q

What are 3 indications for excahnge transfusion in treatment of acute sickle cell crises?

A
  1. Acute chest syndrome
  2. Stroke
  3. Priapism
117
Q

What are 2 ways to treat chronic problems in sickle cell disease?

A
  1. Hydroxycarbamide
  2. Bone marrow transplant
118
Q

How does hydroxycarbamide work to treat chronic problems in sickle cell disease?

A

increases HbF production and helps protect against further crises

119
Q

What is a side effect of hydroxycarbamide that must be monitored for?

A

WCC - suppression can occur

120
Q

When might you offer bone marrow transplant in sickle cell disease?

A

most severely affected chidren who have had stroke, or who do not respond to hydroxycarbamide

121
Q

What is usually the only time you can perform bone marrow donation in sickle cell anaemia?

A

if child has HLA-identical sibling who can donate their bone marrow

122
Q

What is the prognosis of sickle cell disease?

A

cause of premature death due to severe complications

50% with severe form die before age of 40 years

mortality rate in children is 3%, usually from bacterial infection

123
Q

What prenatal diagnosis and screening is performed for sickle cell disease?

A
  • neonatal screening using the dried blood spots (Guthrie test) collected in the first week of life for neonatal biochemical screening.
  • Prenatal diagnosis can be carried out by chorionic villus sampling at the end of the first trimester if parents wish to choose this option to prevent the birth of an affected child
  • also carry screening in mother with blood tests before 10 weeks
124
Q

What is the benefit of early diagnosis of sickle cell disease?

A

allows penicillin prophylaxis to be started in early infancy instead of awaiting clinical presentation, possibly due to a severe infection

125
Q

What is the outlook like for patients with haemoglobin SC disease?

A

nearly normal Hb level, fewer painful crises than those with HbSS but may develop proliferative retinopathy in adolescence

126
Q

What are 2 problems that patients with Hb SC disease may develop?

A
  1. Proliferative retinopathy in adolescence
  2. Osteonecrosis of hips and shoulders
127
Q

What is the management of patients with Haemoglobin SC disease?

A

screening for proliferative retinopathy: eyes should be checked periodically

128
Q

What is required for patients who are sickle cell trait?

A

potential carriers should be screened prior to GA to make sure additional effort to prevent hypoxia is made - sickling possible if exposed to low oxygen tension

129
Q

In which regions does beta-thalassaemia occur most often?

A

people from Indian subcontinent, Mediterranean and Middle East

130
Q

What are the 2 types of beta-thalassaemia?

A
  1. β-thalassaemia major
  2. β-thalassaemia intermedia
131
Q

What causes both types of beta-thalassaemias?

A

severe reduction in the production of β-globin (and thereby reduction in HbA production). All affected individuals have a severe reduction in β-globin

132
Q

What does the severity of beta-thalassaemia depend upon?

A

amount of residual HbA and HbF production

133
Q

What characterises β-Thalassaemia major?

A

This is the most severe form of the disease. HbA (α2β2) cannot be produced because of the abnormal β-globin gene

134
Q

What characterises β-Thalassaemia intermedia?

A

milder and of variable severity. The β-globin mutations allow a small amount of HbA and/or a large amount of HbF to be produced

135
Q

What are 3 key clinical features of beta-thalassaemia?

A
  1. Severe anaemia, which is transfusion dependent, from 3 months to 6 months of age and jaundice
  2. Faltering growth/growth failure.
  3. Extramedullary haemopoiesis
136
Q

When does anaemia first typically present in beta thalassaemia?

A

3-6 months

137
Q

How can extramedullary haemopoiesis be prevented in beta thalassaemia?

A

regular blood transfusions

138
Q

What will happen due to extramedullary haemopoiesis in the absence of treatment?

A

hepatosplenomegaly and bone marrow expansion - latter leads to classical facies with maxillary overgrowth and skull bossing

139
Q

What are 3 aspects of the management of beta thalassaemia?

A
  1. Lifelong monthly transfusions of red blood cells
  2. all patients are treated with iron chelation with subcutaneous desferrioxamine, or with an oral iron chelator drug, such as deferasirox, starting from 2 years to 3 years of age
  3. An alternative treatment for β-thalassaemia major is bone marrow transplantation, which is currently the only cure
140
Q

What is the aim of blood transfusions to treat beta-thalassaemia?

A

maintain the haemoglobin concentration above 100 g/L in order to reduce growth failure and prevent bone deformation

141
Q

What are 2 options for iron chelation in beta-thalassaemia?

A
  1. Subcutaneous desferrioxamine
  2. Oral iron chelator such as deferasirox
142
Q

When can desferasirox (oral iron chelator) be started from?

A

2-3 years of age

143
Q

What does mortality of beta-thalassaemia depend upon?

A

compliance - difficult

144
Q

What is the risk of bone marrow transplant?

A

transplant-related mortality

145
Q

How can a prenatal diagnosis of beta-thalassaemia be made?

A

chorionic villous sample

antenatal blood test before 10 weeks

(+genetic counselling)

146
Q

What is usually the case for heterozygotes for beta-thalassaemia trait?

A

usually asymptomatic - is beta-thalassaemia trait

147
Q

What are the key findings on investigation in beta-thalassaemia trait?

A
  • Most important feature is HbA2
  • in half, mild elevation of HbF level
  • serum ferritin normal
  • red cells hypochromic and microcytic, anaemia mild or absent with disproportionate reduction in MCH (18-22) and MCV (60-70)
  • Red blood cell count usually increased
148
Q

How can beta-thalassaemia trait be differentiated from anaemia?

A

ferritin low in IDA, normal in beta-thalassaemia trait

149
Q

How can you try and avoid unnecessary iron therapy in beta-thalassaemia trait?

A

prior to starting iron supplement, serum ferritin levels should be measured in patients with mild anaemia and microcytosis

150
Q

What is alpha-thalassaemia?

A

healthy individuals have 4 alpha-globin genes

manifestation of alpha-thalassaemia syndromes depends on number of functional alpha-globin genes

151
Q

What is the most severe form of alpha-thalassaemia and what is another name of it?

A

α-thalassaemia major, also known as Hb Barts hydrops fetalis

152
Q

What is the cause of alpha-thalassaemia major?

A

deletion of all four α-globin genes, so no HbA (α2β2) can be produced

153
Q

What region are most patients with alpha-thalassaemia major from?

A

South-East Asian

154
Q

What is the presentation of alpha-thalassaemia major?

A

fetal hydrops (oedema and ascites) from fetal anaemia, which is always fatal in utero or within hours of delivery

155
Q

Who are the only survivors of alpha-thalassaemia major?

A

those who have received monthly intrauterine transfusions until delivery followed by lifelong monthly transfusions after birth

156
Q

How is a diagnosis of alpha-thalassaemia major made?

A

Hb high-performance liquid chromatography (HPLC) or Hb electrophoresis, which shows only, or mainly, Hb Barts

157
Q

What is HbH disease?

A

form of alpha-thalassaemia, when only three of the alpha-globin genes are deleted. causes mild-moderate anaemia but occasional patients are transfusion dependent

158
Q

What is alpha-thalassaemia trait?

A

deletion of one or two alpha-globin genes

usually asymptomatic and anaemia is mild or absent

red cells may be hypochromic and microcytic, which may cause confusion with iron deficiency

159
Q

What are 5 clinical features and complciations of beta-thalassaemia major?

A
  1. Pallor
  2. Jaundice
  3. Bossing of the skull, maxillary overgrowth
  4. Splenomegaly and hepatomegaly
  5. Need for repeated blood transfusions + complications
160
Q

What are 4 types of complications of long-term blood transfusion in children?

A
  1. Iron deposition
  2. Antibody formation: allo-antibodies to transfused red cells in the patient make finding compatible blood very difficult
  3. Infection - hep A, B, C, HIV, malaria, prions
  4. Venous acces (common problem) - often traumatic in young children, central venous access device (e.g. Portacath) may be required, predispose to infection
161
Q

What are 6 effects of iron deposition from blood transfusions in thalassaemia?

A
  1. Heart - cardiomyopathy
  2. Liver cirrhosis
  3. Diabetes (pancreas effects)
  4. Pituitary gland - impaired growth and sexual maturation
  5. Skin - hyperpigmentation
  6. Infertility
162
Q

What are 2 causes of anaemia in the newborn?

A
  1. Reduced red blood cell production
  2. Increased red cell destruction (haemolytic anaemia)
163
Q

What are 2 causes of reduced red blood cell production?

A
  1. Congenital infection with parvovirus B19
  2. Congenital red cell aplasia (Diamond-Blackfan anaemia)
164
Q

What is the diagnostic clue to reduced red blood cell production in anaemia in the newborn?

A

Hb is low, red blood cells look normal; clue is that reticulocyte count is low and the bilirubin is normal

165
Q

What are 4 causes of haemolytic anaemia in the newborn?

A
  1. Immune e.g. haemolytic disease of the newborn
  2. Red cell membrane disorders e.g. hereditary spherocytosis
  3. Red cell enzyme disorders e.g. G6PD deficiency
  4. Abnormal haemoglobins e.g. alpha-thalassaemia major
166
Q

What are the diagnostic clues to a haemolytic anaemia?

A

increased reticulocyte count (due to increased red cell production to compensate for the anaemia) and increased unconjugated bilirubin (due to increased red cell destruction with release of this bile pigment into the plasma)

167
Q

What test can be done to confirm immune haemolytic anaemia of the newborn i.e. ABO or Rh incompatibility?

A

Direct Coombs test - only positive in antibody-mediated anaemias and so is negative in all the other types of haemolytic anaemia

168
Q

What are the 3 main causes of blood loss in the newborn?

A
  1. Feto-maternal haemorrhage (occult bleeding into the mother)
  2. Twin-to-twin transfusion (bleeding from one twin into the other one)
  3. Blood loss around the time of delivery (e.g. placental abruption)
169
Q

What is the diagnostic clue for blood loss as a cause of anaemia in the neonate?

A

severe anaemia with raised reticulocyte count and normal bilirubin

170
Q

What are the 4 main causes of anaemia of prematurity?

A
  1. Inadequate erythropoietin production.
  2. Reduced red cell lifespan.
  3. Frequent blood sampling whilst in hospital.
  4. Iron and folic acid deficiency (after 2–3 months).

Paeds: Gastro and Growth (14 decks)

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