neonatal jaundice

Question 1

how is bilirubin produced?

Answer 1

from heme, from breakdown of rbcs

Question 2

how is bilirubin metabolised?

Answer 2

Unconjugated bilirubin (water insoluble) is metabolised by the liver to conjugated bilirubin (water soluble) which can be excreted into the gut
Liver metabolism relies on bilirubin uptake via ligandin and then conjugation by uridine diphosphoglucuronyltransferase (UDPGT)

Question 3

why are newborns often jaundiced?

Answer 3

Both ligandin and UDPGT are low in the new born making newborns inefficient at managing bilirubin
In newborns a percentage reverts to unconjugated bilirubin and is recirculated into the blood stream – enterohepatic circulation

Question 4

how does Gilbert’s disease affect bilirubin?

Answer 4

mutation of UGT1A1 gene reduces bilirubin uridine diphosphate glucuronosyltransferase by around 30% (bilirubin-UGT) and can make jaundice worse

Question 5

what is kernicterus?

Answer 5

brain damage resulting from high levels of bilirubin crossing the blood brain barrier causing encephalopathy which leads to kernicterus

Question 6

what are risk factors for jaundice in neonates?

Answer 6

prematurity, blood group difference, forceps delivery, maternal age >25

Question 7

how do you do phototherapy on neonates?

Answer 7

incubator with blue light, eye mask, no clothes on other than nappy

can come out of incubator under biliblanket to breastfeed as this should always be continued

Question 8

what are the causes of neonatal jaundice?

Answer 8

physiological- normal and seen in lots of babies
pathological- haemolysis, sepsis, metabolic disorders, liver disease

Question 9

what are the time frames of neonatal jaundice?

Answer 9

Early = 0-24 hours
Physiological = 24-72 hours
Late = > 14 weeks in term and 21 days in preterm

Question 10

what causes physiological jaundice?

Answer 10

Increased production; Foetal RBC life span 2/3 of adults, High Hct, Bruising
Decreased uptake and binding by liver cells
Decreased conjugation(most important)
Decreased excretion
Increased enterohepatic circulation of bilirubin

Question 11

what are causes of early pathological jaundice?

Answer 11

haemolysis with excessive production of bilirubin, or sepsis (also rarely hepatitis)

Question 12

what investigation do you do for early pathological jaundice?

Answer 12

total bilirubin concentration
maternal & baby’s blood group
Direct Agglutination Test (detects antibodies on the baby’s red cells), and elution test to detect anti-A or anti-B antibodies on baby’s red cells
FBC- look for Hb level, haemolysis, unusual rbc shape, infection

Question 13

what are the symptoms of neonatal bilirubin encephalopathy?

Answer 13

lethargy
poor feeding
temperature instability
hypotonia
arching of the head, neck and back (opisthotonos)
spasticity
seizures

Question 14

should you always investigate neonatal jaundice?

Answer 14

yes because pathological jaundice can still appear in physiological time frame

Question 15

what are the causes of persistent unconjugated hyperbilirubinaemia?

Answer 15

Breast milk jaundice (diagnosis of exclusion, cessation of breast feeding is not advised)
Poor milk intake
Haemolysis
Infection (especially urinary tract infection)
Hypothyroidism

Question 16

what is the most important investigation for late pathological jaundice?

Answer 16

whether the elevated bilirubin is mostly unconjugated or conjugated (substantial increase = conjugated >15% of total)

Question 17

what are the causes of persistent conjugated hyperbilirubinaemia?

Answer 17

hepatitis usually (can be other infections or metabolic causes though)
or biliary atresia- obstructive jaundice that is fatal without surgery

Question 18

what is the treatment of neonatal jaundice?

Answer 18

adequate feeding & hydration
phototherapy
rarely exchange transfusion in haemolytic disease
IV immunoglobulin in babies with haemolysis and high levels of phototherapy isn’t working