Neonatal and Newborn Flashcards
What % of babies are visibly jaundiced in the first week of life?
50%
What is jaundice?
Jaundice = state of hyperbilirubinaemia
Serum bilirubin exceeds 85μmol/L
Describe the stages of bilirubin metabolism
1) Haemoglobin (from RBCs) is broken down into haem and iron in the spleen
2) Bilirubin is the main breakdown product of haem
3) Unconjugated bilirubin = lipid soluble. It is transported round the blood bound to albumin
4) In the liver, it is actively transported into hepatocytes where it is conjugated with glucoronic acid by the enzyme UDPGT
5) Conjucated bilirubin = water soluble. It is stored in the gallbladder and excreted as a component of bile
6) Bile is broken down by gut bacteria into stercobilinogen and urobilinogen
7) A small amount of urobilinogen is reabsorbed and then excreted by the kidneys
What are the 3 types of jaundice?
1) Pre-hepatic
2) Hepatocellular / intrahepatic
3) Post-hepatic
Outline what pre-hapatic jaundice is
What levels would be raised?
Excessive RBC breakdown overwhelms the livers ability to conjugate bilirubin
= Unconjugated hyperbilirubinaemia
Any bilirubin that managed to become conjugated will be excreted normally, it is unconjugated bilirubin that remains in the blood stream to cause jaundice
Outline what hepatocellular / intrahepatic jaundice is
What levels would be raised?
Results from dysfunction of the liver itself. Damaged hepatocytes lose the ability to metabolise and excrete bilirubin
= Unconjugated hyperbilirubinaemia
The small bile ducts may also become damaged or obstructed, meaning conjugated bilirubin leaks into the blood
= Conjugated hyperbilirubinaemia
Thus hepatic jaundice = MIXED PICTURE
Outline what post-hepatic jaundice is
What levels would be raised?
Obstruction of biliary drainage
= Conjugated hyperbilirubinaemia
What is physiological jaundice in a neonate?
= Slow change to conjugation
In foetus, bilirubin stays unconjugated to allow placental excretion
After birth, conjugation and hepatic excretion takes over
If this happens slowly = physiological (hepatocellular) jaundice
THIS IS NOT PATHOLOGICAL
Is jaundice within the first 24 hours of life concerning?
YES
JAUNDICE WITHIN THE FIRST 24HRS OF LIFE IS ALWAYS PATHOLOGICAL
What are some causes of neonatal jaundice <24hrs? (Unconjugated and conjugated)
Unconjugated:
- Haemolytic disease
- Neonatal Sepsis
Conjugated:
- Neonatal hepatitis
- Congenital infections (rubella, CMV, syphilis)
What are some causes of neonatal jaundice 24hrs - 2 weeks? (Unconjugated and conjugated)
Unconjugated:
- Physiological (exacerbated by bruising, polycythaemia, dehydration)
- Hypothyroidism
- Haemolysis / sepsis
Conjugated:
- Neonatal hepatitis
- Congenital infections (rubella, CMV, syphilis)
What are some causes of neonatal jaundice >2 weeks? (Unconjugated and conjugated)
Unconjugated:
- Breast milk jaundice
- Haemolysis / sepsis
- Hypothyroidism
Conjugated: - Biliary atresia - Choledochal cyst - Neonatal hepatitis (alpha-1 antitrypsin, TORCH, galactosaemia, CF)
What is breast feeding jaundice and what is breast milk jaundice?
Breast feeding jaundice = failure to establish breast feeding and so child dehydrated (thus less bilirubin excreted in urine so builds up)
Breast milk jaundice = substance passes through breast milk into baby which increases activity of glucouronidase, leading to build up of bilirubin NB not a reason to stop breast feeding
Jaundice within first 24 hrs is usually due to haemolysis. List 3 causes of haemolysis leading to neonatal jaundice
1) ABO incompatibility
- mOther has antibodies against bAby
2) Rhesus
- Rh-ve mother exposed to Rh+ve red cells during first pregnancy. In following pregnancy, she produces anti-D which breaks down child’s red cells = alloimmunisation
3) G6PD deficiency
- Lack of G6PD leads to rapid haemolysis during oxidative stress eg infection, medication, lava beans (X- linked recessive)
List some risk factors for neonatal jaundice (5)
1) Premature / low birth weight
2) Breast-fed babies
3) Diabetic mother
4) Male
5) East Asian ethnicity
