Flashcards in Neonatal jaundice Deck (14)
Go through the normal progression of bilirubin concentrations in a healthy neonate. What percentage of neonates may become jaundiced?
At birth, neonates aren't jaundiced as placenta has been able to filter bilirubin out. Usually have bilirubin concentration 30-40umol/L (adults have 20umol/L)
Bilirubin quickly increases after birth and peaks around 4 days, before liver enzymes are fully active and bilirubin starts to diminish. May not reach 20umol/L until a few weeks.
50% of neonates may become jaundiced
Give 4 reasons why neonates have a greater propensity to become jaundiced than adults
RBCs only have a 60 day half life (= greater haemolysis)
Haem metabolism isn't as quick (liver enzymes yet to be induced)
Neonates have a greater Hb concentration (which is why they look so red) = more Hb to metabolise
What bilirubin concentration is required to see jaundice in a neonate?
Name 2 reasons why neonatal jaundice may be an important clinical sign
Severe jaundice can cause kernicterus and cerebral damage
Severe jaundice can also reflect an underlying disease in haem metabolism or haemolysis
Name 3 instances where you would worry about neonatal jaundice
Early jaundice - less than 24 hours and over 100 umol/L
If conjugated bilirubinaemia is severely high (physiological jaundice usually unconjugated)
If bilirubin stays high for too long (over 100 for over 2 weeks)
What values make you worry about early jaundice in a neonate? Give 4 causes of early jaundice
Bilirubin > 100umol/L
Red cell isoimmunisation (ABO, Rh, Kell etc)
Funny shaped cells (sickle cell, hereditary spherocytosis)
Metabolic (G6PD deficiency)
Name 3 blood group incompatibilities that cause severe haemolysis, not mild
D, Kell, c - ABO usually mild (as only a small percentage of antibodies switch to IgG and cross placenta)
What test should you do if you suspect a blood group incompatibility causing early haemolysis?
Direct Coombs test to look for presence of autoantibodies
Why does alpha but not beta thalassaemia major cause early haemolysis?
Neonatal Hb is in process of switching from A2G2 to A2B2 conformation. Alpha thalassaemia = unstable A2 = will get haemolysis from birth. Beta thalassaemia = unstable B2 = will only get clinically significant haemolysis after transition to adult haemoglobin
Name 3 things that can trigger G6PD
Moth balls (napthalene), aspirin, anti-malarial drugs
Name 3 causes of severely high conjugated bilirubin in a neonate
Feeding problems (means that less is excreted in bile)
Bowel obstruction (less excreted in bile)
Trauma during birth
Name causes of prolonged raised bilirubin in a neonate (3 causes of unconjugated and 3 causes of conjugated bilirubin)
Unconjugated - breastmilk jaundice, congenital hypothyroidism, infection (usually UTI)
Conjugated - biliary atresia, metabolic (galactossaemia), genetic (alpha-1 anti-trypsin deficiency)
How can you detect foetal haemolysis in utero? Name 2 management strategies
With MCA Doppler U/S, looking for increased peak systolic velocity (sign of anaemia). If severe, can manage with immediately delivery, or in utero transfusion (via umbilical vein or into peritoneum)