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Give 3 reasons why newborns become visibly jaundiced?
- Increased breakdown of Hb as high conc at birth
- Their RBC lifespan is shorter (70d)
- Hepatic bilirubin METABOLISM is less efficient in the first few days of life
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Why is neonatal jaundice important?
- Could be sign of other disease eg infection, haemolytic anaemia
- Kernicterus
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What is kernicterus? Cause?
- ENCEPHALOPATHY
- Due to deposition of unconjugated bilirubin in BASAL GANGLIA and BRAINSTEM NUCLEI
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When does kernicterus occur?
- When level of unconjugated bilirubin EXCEEDS ALBUMIN binding capacity of bilirubin of the blood
- As the free bilirubin is FAT SOLUBLE – it can cross BBB
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What are the neurotoxic effects in kernicterus?
- Vary from transient disturbance
- Severe damage
- Death
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What are acute manifestations of kernicterus?
Lethargy and poor feeding
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What are symptoms/signs of severe kernicterus
- Irritability
- Increased muscle tone – cause baby to lie with ARCHED BACK = OPISTHOTONUS
- Seizures
- Coma
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What are the 3 consequences of infants who survive severe kernicterus?
- Choreoathetoid cerebral palsy – due to basal ganglia damage
- Learning difficulties
- Sensorineural deafness
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What has reduced the incidence of kernicterus due to rhesus haemolytic disease?
Prophylactic anti-D immunoglobulin for Rh –ve mothers
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What levels of bilirubin need to be reached for babies to become clinically jaundiced?
80-120 umol/L
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How do you classify the causes of neonatal jaundice?
- Age at onset
- <24h of age
- 24h – 3 weeks
- > 3 weeks
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What are the 3 main large categories of jaundice < 24h age?
- Haemolytic disorders
- Congenital infection
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Is jaundice in the 1st 24 hours of life physiological or pathological?
Always pathological
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What are the 5 causes of haemolytic disorders that cause jaundice <24h age?
- 1. Rhesus haemolytic disease of the newborn
- 2. ABO incompatibility
- 3. G6PD deficiency
- 4. Hereditary spherocytosis
- 5. Pyruvate kinase deficiency
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If rhesus haemolytic disease has not been identified antenatally, how could a severely affected infant be born?
- Hydrops
- Hepatosplenomegaly
- Anaemia
- Severe jaundice, rapidly developing
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Which other blood groups apart from Rhesus antigens could antibodies be formed to?
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What cause of haemolytic disease is now more common than rhesus?
ABO incompatibility
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What type of Ig are most ABO antibodies? And can these cross placenta?
- IgM
- These do not cross placenta
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Which blood group in the mother can cause haemolysis in baby, why? What blood group is the baby usually?
- Group O women
- Some have IgG anti-A-haemolysin in the blood which can cross the placenta and haemolyse the RBC of a group A infant
- Occasionally group B infants are affected by anti-B haemolysins
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What is the haemolysis in ABO incompatibility like compared to Rhesus?
- Less severe
- No hepatosplenomegaly
- Hb normal or slightly reduced
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Which test is positive in ABO incompability?
- Direct Antibody Test = Coombs test
- Demonstrates antibody on surface of RBC
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When does the jaundice in ABO incompatibility usually peak?
First 12-72 hours
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What is the most common cause of severe neonatal jaundice worldwide needed exchange transfusion?
G6PD deficiency
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Which populations are more affected by G6PD deficiency?
- Mediterranean
- Middle east
- Oriental
- Afro-caribbean
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What is the cause of G6PD deficiency?
X-linked recessive
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What happens in G6PD deficiency?
- RBC do not generate enough glutathione to protect the cell from oxidant agents
- So break down
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If G6PD deficiency a disease of males or females?
- Males more severely affected
- But females can manifest the phenotype
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What are the main precipitants for acute haemolysis in G6PD deficiency?
- Infection
- Drugs
- Fava beans - divicine
- Mothballs – naphthalene
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What is the most common precipitating factor in G6PD deficiency?
Infection
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Which drugs can cause haemolysis in G6PD deficiency?
- Antimalarials: chloroquine, primaquine, quinine
- Antibiotics: sulphonamides, quinolone
- Analgesic : aspirin high dose
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Which foods need to be avoided in G6PD deficiency?
Fava beans (broad beans)
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Is the haemolysis in G6PD deficiency intravascular or extravascular?
Intravascular
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What other symptoms is acute haemolysis in G6PD deficiency assoc with?
- Fever
- Malaise
- Dark urine – due to Hb and urobilinogen
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How is the diagnosis of G6PD deficiency made?
- Measure G6PD activity in RBC
- Note during acute haemolytic crisis, G6PD levels might be misleadingly high due to higher enzyme conc in reticulocytes – which are made in increased numbers in response to haemolysis
- So a repeat assay is needed in the ‘steady state’ to confirm diagnosis
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What is the mainstay of management of G6PD deficiency?
- Give parents advice about SIGNS of acute haemolysis: jaundice, pallor, dark urine
- List of drugs, chemicals, food to avoid
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What is the inheritance of spherocytosis?
Autosomal dominant
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What is the defect in spherocytosis? And how does this lead to haemolysis?
- Abnormality in SPECTRIN – a major supporting component in RBC membrane
- RBC shape becomes spheroidal and less deformable leads to destruction in microvasculature in SPLEEN (extravascular haemolysis)
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What are the clinical features of spherocytosis?
- Mild anaemia
- Jaundice, hyperbilirubinaemia
- Splenomegaly
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What are the 2 main complications of spherocytosis?
- Aplastic crisis 2ry to parvovirus B19 infection
- Gallstones due to increased bilirubin excretion
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How is the diagnosis of spherocytosis confirmed?
- Osmotic fragility test: in hypotonic solutions spherocytes rupture more easily than biconcave RBC as they have maximal SA:vol ratio
- Also see spherocytes on peripheral blood film
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What is Rx of spherocytosis?
- Folic acid to meet increased demands of marrow
- Splenectomy if severe (remember post splenectomy care…Pneumo, Meningo, Hib vaccine, pen proph)
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What type of bilirubin does haemolysis produce?
Unconjugated (not water soluble, fat soluble so can cross BBB)
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What type of bilirubin do you get from jaundice due to congenital infection?
Conjugated (water soluble as bound to glucuronic acid)
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What is the most common cause of jaundice at 2 days to 3 weeks of age?
- Physiological jaundice – adapting to transition from fetal life
- Only use this term after other causes have been considered
- (due to liver enzyme immaturity and increased load of bili from RBC breakdown)
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When does physiological jaundice usually peak?
Day 3
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How does feeding affect jaundice?
Jaundice is more common in breast fed babies
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What type of hyperbilirubinaemia do you get with breast fed babies?
Unconjugated
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What is thought to be the cause of breast milk jaundice?
Increased enterohepatic circulation of bilirubin
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What can exacerbate breast milk jaundice?
- Delay in establishing breast feeding – so inadequate bowel movements to remove bilirubin from body
- – then get dehydrated. May need iv fluids to correct it
- What is the advice in breast milk jaundice?
- Breast feeding should be continued
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How long can breast milk jaundice continue up to?
6 weeks
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Which infections can jaundice 2days – 2 weeks?
UTI
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What other features can exacerbate a neonate’s jaundice?
- Bruising
- Polycythaemia hct>0.65
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Which rare syndrome can cause very high levels of unconjugated bilirubin?
- Crigler-Najjar syndrome
- Enzyme glucuronyl transferase is deficient or absent
- Rare
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What is the definition of prolonged jaundice in a term baby?
> 14 days
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What is the definition of prolonged jaundice in a preterm baby?
> 21 days
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What are the causes of PROLONGED UNCONJUGATED hyperbilirubinaemia?
- Breast milk jaundice: most common, disappears 4-5weeks
- Infection – UTI
- Congenital hypothyroidism – may get prolojnged jaundice before symptoms of hypothyroidism occur (coarse facies, dry skin, hypotonia, constipation). Should be identified on neonatal screening – Guthrie test
- (also excess haemolysis: G6PD deficiency, ABO incompatibility)
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How can you tell from mother’s history that it is CONJUGATED hyperbilirubinaemia?
- Pale stools
- Dark urine
- Poor weight gain
- (hepatomegaly)
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How do you tell on blood test that it is CONJUGATED?
>15% of total bilirubin is conjugated
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What are the 2 main causes of prolonged neonatal jaundice with CONJUGATED hyperbilirubinaemia?
- Biliary atresia
- Neonatal hepatitis syndrome
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Why is it important to diagnose biliary atresia promptly?
As delay in surgical Rx can adversely affect outcome
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How is the severity of neonatal jaundice assessed?
- 1. Clinical assessment – blanch skin to assess jaundice (may underestimate in dark skin), check for hepatosplenomegaly (means it is not physiological jaundice)
- 2. Bilirubin level – transcutaneous or blood. Must have plasma level in significantly jaundiced baby. Plot serial measurements on chart – to see rate of change and anticipate need for treatment before rises to dangerous level (chart is gestation specific)
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What is the definition of physiological jaundice (4 points)
- Onset after 24 hours of birth
- Resolves within 2 weeks
- More than 85% UNCONJUGATED
- Total bilirubin <350
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How does gestation affect management of neonatal jaundice? Why?
- Lower treatment threshold if preterm
- As have lower albumin levels – so higher bilirubin levels (higher risk kernicterus)
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Which risk factors for jaundice need to be asked about?
- Haemolysis: antenatal antibodies
- Check if mother is group O blood
- Origin- Mediterranean, Far Eastern or Afro-Caribbean (G6PD deficiency)
- Sepsis, unwell, acidosis, low serum albumin
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How do you check the need for treatment in jaundice?
- Plot bilirubin on chart relating bilirubin with age
- Plot rate of change of bilirubin
- Allow for gestation, age and RF
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What are the 2 main forms of Rx for jaundice?
- Phototherapy – most widely used therapy
- Exchange transfusion – for severe cases
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How does phototherapy work for jaundice?
- Blue light (not UV)
- Wavelength 450nm
- Converts bilirubin in the skin and superficial capillaries into harmless water soluble metabolites
- Which are excreted in urine and through bowel
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What other ‘nursing’ techniques are used during phototherapy?
- Eyes covered to prevent discomfort
- Additional fluids given to counteract increased losses from skin
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What are the 2 main forms of phototherapy?
- Over head light source
- Fibre optic blanket applied directly to skin
- Can use both for maximum phototherapy = double/intensive phototherapy
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When is exchange transfusion required for jaundice Rx?
- If bilirubin rises to a potentially dangerous level
- Especially if there is anaemia from haemolysis
- Or low serum albumin
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What are the advantages of exchange transfusion?
- Rapidly reduces level of circulating bilirubin
- In isoimmune haemolytic disease also removes circulating antibodies and corrects anaemia
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What is the traditional method of transfusion?
Via Umbilical artery and vein catheters
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How much blood is given during exchange transfusion?
- Twice the infants blood volume
- Ie 2 x 80ml/kg is exchanged over 2 hours
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