Jaundice Flashcards
how common is jaundice
very common
60% of term
80% of preterm
at what age does most jaundice appear
day 2-3 of life
what clinical sign is due to high levels of bilirubin
jaundice
what produces bilirubin
breakdown of red blood cells
what does haem breakdown produce
unconjugated bilirubin
what is most unconjugated bilirubin bound to when circulating
albumin
some bilirubin is free in plasma - why do we worry about this stuff
it can cross the blood brain barrier
heme —> _______ —-> bilirubin
biliverdin
which type of bilirubin is water insoluble
unconjugated
which type of bilirubin is water soluble
conjugated
where is unconjugated bilirubin metabolised to conjugated bilirubin
liver
what is unconjugated bilirubin sometimes called
indirect bilirubin
what is conjugated bilirubin sometimes called
direct bilirubin
what enzyme metabolises/causes conjugation of bilirubin
UDPGT
why are newborns inefficient at managing bilirubin
ligandin and UDPGT are low in the newborn
what does enterohepatic circulation refer to in newborns (bilirubin)
a percentage of the conjugated bilirubin that passes into the gut reverts to unconjugated bilirubin and is recirculated into the bloodstream.
give an example of a disease causing an enzyme abnormality that affects conjugation of bilirubin
Gilbert’s disease
which gene is mutated in gilbert’s disease
UGT1A1
what does unconjugated bilirubin crossing the BBB cause
encephalopathy which can lead to kernicterus
what additional factors are required to put a baby at significant risk of encephalopathy
decreasing gestation
asphyxia
acidosis
hypoxia
hypothermia
meningitis
sepsis
why do we worry about jaundice
because of the neurological effects it can have
Pathological jaundice
physiological jaundice that’s too high
haemolysis
sepsis
metabolic disorders
liver disease
which timing of jaundice is considered pathological until proven otherwise
early jaundice - 0-24hrs
in what time frame does physiological jaundice usually appear
24-72hrs
late prolonged jaundice
persisting over 14 days in term and 21 days in preterm
why does physiological jaundice develop
- increased bilirubin production; foetal RBC lifespan is shorter, high Hct, bruising
- decreased uptake and binding by liver cells (normal development of baby)
- decreased conjugation (most important)
- decreased excretion
- increased enterohepatic circulation of bilirubin
are babies great at conjugating bilirubin
nope
what underlying cause should you watch out for in early jaundice
sepsis
what is jaundice under a day old usually due to
a haemolytic event, with excessive production of bilirubin
why might a baby be born with jaundice (so like immediate jaundice)
severe haemolysis
hepatitis (unusual)
causes of haemolysis
ABO incompatibility
Rh immunisation
Sepsis
when would you consider hepatitis as a cause of haemolysis
if there is substantial elevation of conjugated bilirubin (>15% of the total)
which tests detect antibodies on the baby’s red cells
Direct Agglutination Test
elution test
what test would be positive in blood group incompatibility
Direct Agglutination Test (DAT)
what would Direct Agglutination Test result be in haemolysis
negative
bilirubin encephalopathy symptoms
- lethargy
- poor feeding
- temperature instability
- hypotonia
bilirubin encephalopathy severe and very rare symptoms
- arching of head, neck and back (Opisthotonos)
- spasticity
- seizures
conjugated bilirubin above which percentage needs investigating?
> 15% of the total bilirubin
causes of persistent UNconjugated hyperbilirubinaemia
- breast milk jaundice
- poor milk intake
- haemolysis
- infection (especially UTI)
- hypothyroidism
what does persistent CONJUGATED hyperbilirubinaemia signify
a hepatitis
what is biliary atresia
a rare condition causing obstructive jaundice
a section of the bile duct is either narrowed or absent
biliary atresia symptoms
jaundice
pale, clay coloured stools
dark urine
what operation do babies with biliary atresia need before 3 months of age
Kasai portoenterostomy
