Neonatal Jaundice

Question 1

What are the cut offs for bilirubin to cause clinical jaundice?

Answer 1

Sclera: 40-50
Skin: 80-100 - more like 150 in babies

Question 2

What is the normal bilirubin range in adults?

Answer 2

20

Question 3

Why are babies pink?

Answer 3

Higher haemoglobin concentration

Question 4

What is kerniterus?

Answer 4

• Damage to brain due to high levels of unconjugated bilirubin - greater than the ability of albumin to bind it (only unbound can cross the BBB)
• Particularly affects the basal ganglia

Question 5

What is the bilirubin cut off for the development of kerniterus?

Answer 5

340umol/L

Question 6

What causes high conjugated bilirubin?

Answer 6

Biliary atresia

Liver dysfunction

Question 7

What causes liver dysfunction in neonates?

Answer 7

Hepatitis 
CF
Biliary atresia
TPN
Galactesaemia

Question 8

What causes persistent jaundice?

Answer 8

Breast milk jaundice

Hypothyroidism

Question 9

Why does bilirubin increase after birth in newborns? When does it peak in normals and preterms respectively?

Answer 9

Immaturity glucuronyl transferase system which has only started working at birth (bilirubin isn’t conjugated in utero)
Haemolysis of excess fetal hb

3 days in health normal
5 days in preterm

Question 10

What is a useful of categorising the causes of jaundice in the newborn?

Answer 10

Jaundice in the first 24 hours
Too high in the medium terms (2-10 days)
Ongoing jaundice

Question 11

What are the causes of jaundice in the first 24 hours?

Answer 11

○ Haemolysis 
		§ ABO
			□ Only if maternal O with IgG anti-A, -B, Otherwise IgM doesn't cross
		§ Kell
		§ Anti-D
		§ "c" 
○ Enzyme deficiency
		§ G6PD
			□ X-linked therefore usually males
			□ Triggered by naphthalene, anti-malarials, aspirin 
○ Membrane disorders 
		§ Hereditary spherocytosis 
			□ Autosomally inherited

Question 12

What are causes of jaundice in the intermediate period?

Answer 12

○ Same causes of haemolysis
○ Sepsis
○ Underfeeding and delayed gastric emptying (bilirubin is reabsorbed) 
○ Birth trauma 
	§ Bruising, cephal haematoma

Question 13

What are causes of late jaundice?

Answer 13

○ Persistent jaundice
§ Breast milk jaundice
§ Hypothyroidism
○ Sepsis

Question 14

How do you Ix jaundice in the newborn?

Answer 14

Direct Coombs test (aka DAT)
Fetal blood group
Maternal blood group 
Hb
Blood film

Question 15

What is the most important DDx for jaundice + lethargy?

Answer 15

Sepsis

Question 16

How is jaundice managed?

Answer 16

Conservative management
Phototherapy
Exchange transfusion

Question 17

How does phototherapy work?

Answer 17

Isomerisation of unconjugated bilirubin causes it to become water soluble and excretable by the liver and kidneys

Question 18

What is kernicterus?

Answer 18

Severe sequelae of marked unconjugated neonatal hyperbilirubinaemia

Question 19

What is the pathophysiology of kernicterus?

Answer 19

Unconjugated bilirubin exceeds the ability of the albumin to bind it and crosses the BBB where it is toxic, particularly to the basal ganglia, and causes transient encephalopathy or permanent brain damage

Question 20

What are the possible long term sequelae of kernicterus?

Answer 20

Choreoathetoid CP
Intellectual disability
Paralysis of upward gaze
High-frequency sensorineural hearing loss