neonatal jaundice

Question 1

what is jaundice?

Answer 1

-yellow discolouration of skin and sclera due to high levels of bilirubin

Question 2

how does jaundice tend to appear on neonates?

Answer 2

cephalopods-caudal progression (face to feet)

Question 3

True/ False Jaundice is physiologically normal in babies

Answer 3

True

Question 4

how is bilirubin produced?

Answer 4

• from the breakdown of red blood cells and is produced from heme
• heme breakdown produces unconjugates bilirubin which mostly circulates bound to albumin

Question 5

how does bilirubin travel in the body?

Answer 5

• unconjugated bilirubin circulates bound to albumin

- some bilirubin is free in plasma and can pass across the blood brain barrier

Question 6

is unconjugated bilirubin water soluble or insoluble?

Answer 6

insoluble and so most be metabolised in the liver into conjugated bilirubin which is water soluble to be excreted from the gut

Question 7

is conjugated bilirubin insoluble or soluble in water?

Answer 7

soluble and so unconjugated bilirubin which is insoluble must be metabolised into soluble conjugated bilirubin which can be excreted from the gut

Question 8

what does liver metabolism rely on?

Answer 8

-bilirubin uptake via ligandin and then conjugation by uridine diphosphoglucuronyltransferase (UDPGT)

Question 9

what are the levels like of ligandin and UDPGT in a newborn and what effect does this have?

Answer 9

ligandin=low
UDPGT=low

this means there is less uptake of bilirubin into the liver and so are inefficient at managing bilirubin

Question 10

what is enterohepatic circulation?

Answer 10

-some newborns revert to unconjugated bilirubin and is recirculated into the blood stream

Question 11

what enzyme abnormalities may affect bilirubin metabolism?

Answer 11

Gilberts disease

Question 12

what causes Gilberts disease?

Answer 12

mutation in UGT1A1 gene

Question 13

what effect does Gilberts disease have?

Answer 13

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

Question 14

What can high levels of unconjugated bilirubin cause?

Answer 14

-can cross the BBB and cause encephalopathy which can lead to Kernicterus (cerebal palsy related to bile)

Question 15

when does physiological jaundice appear in neonates?

Answer 15

24-72 hours

Question 16

when does early jaundice appear in neonates?

Answer 16

0-24 hours

Question 17

when does late jaundice appear in neonates?

Answer 17

> 14 weeks in term and 21 days pre term

Question 18

what are some causes of pathological jaundice?

Answer 18

• haemolysis
• sepsis
• metabolic disorders
• liver disease

Question 19

what causes physiological jaundice in neonates?

Answer 19

• increased production of bilirubin
• foetal RBC have less of a lifespan than adults (2/3rds of an adult)
• babies born with high hematocrit (proportion of red blood cells in their blood)
• babies are often bruised
• decreased uptake and binding of bilirubin in liver cells leading to decreased conjugation (most important)
• increased enterohepatic circulation of bilirubin

Question 20

is it normal for a baby to jaundice <24 hours of age?

Answer 20

no- it is almost always pathological

Question 21

what causes early jaundice?

Answer 21

• usually due to haemolysis with excessive production of bilirubin
• can be sepsis or infection

Rarer causes:

• other blood grop incompatibilities
• red cell enzyme defects e.g. G6PD deficiency
• red cell membrane defecrs e.g. hereditary spherocytosis
• hepatitis

Question 22

what can cause a baby to be born jaundiced?

Answer 22

• severe haemolysis

- hepatitis (unusual)

Question 23

what may cause haemolysis?

Answer 23

• ABO incompatibility
• Rh immunisation
• sepsis

Question 24

what is ABO incompatibility?

Answer 24

• a disease that causes haemolysis and so jaundice

- happens when the mothers blood type is O, and her baby’s blood type is A or B

Question 25

when should hepatitis be considered as a reaon for causing early jaundice?

Answer 25

-if there is substantial elevation of conjugated bilirubin (>15% of the total)

Question 26

what are investigations of early jaundice?

Answer 26

- total bilirubin concentration (SBR) - maternal blood group and antibody titres (if Rh negative) - baby's blood, Direct Agglutination Test (detects antibodies on the baby's red cells), the eulation test to detect anti-A or anti-B antibodies on baby' red cells - FBC, CRP - if clinical concern measure conjugated bilirubin

Question 27

what investigations should be done for suspected haemolysis?

Answer 27

- blood group incompatibility (most commonly Rhesus or ABO incompatibility) - can occur in sepsis but it is rare - can be due to Glucose 6 phosphate dehydrogenase deficiency

Question 28

what tests must be done for suspected haemolysis?

Answer 28

Direct Agglutination test (DAT): - Blood group incompatibilities (most commonly Rhesus or ABO incompatibility) can be identified with a positive DAT - Sepsis would test negative on DAT Check infants blood group for comparison with mothers

Question 29

what test would be done to test for blood group incompatibility such as Rhesus or ABO incompatibility?

Answer 29

Direct Agglutination Test (DAT) and it would be positive

Question 30

how does bilirubin cause encephalopathy?

Answer 30

it crosses the blood brain barrier (BBB) and affects the brain

Question 31

how does bilirubin encephalopathy present in neonates?

Answer 31

- lethargy - poor feeding - temperature instability - hypotonia - arching of the head, neck and back

Question 32

what may cause serum bilirubin to be too high causing jaundice?

Answer 32

- mild dehydration/insufficient milk supply - breakdown of extravasated blood e.g. cephalohaematoma, bruising - some 'normal' physiological - haemolysis (continuing causes as discussed under too early) - infection - increased enterohepatic circulation (gut obstruction)

Question 33

what is the major differential in diagnosis of 'too long' pathological jaundice?

Answer 33

-whether the elevated bilirubin is mostly unconjugated or whether the conjugated fraction is substantially increased (>15% of total)

Question 34

what is the most common cause of unconjugated prolonged jaundice?

Answer 34

breast milk jaundice (cessation of breast feeding is not advised)

Question 35

what are some causes of persistent unconjugated hyperbilirubinemia causing jaundice?

Answer 35

- breast milk jaundice (most common) - poor milk intake - haemolysis - infection (especially UTI) - hypothyroidism

Question 36

True or false conjugated hyperbilirubinaemia can be normal

Answer 36

False- it is always abnormal can be hepatitis or biliary atresia

Question 37

what does conjugated hyperbulirubinaemia suggest?

Answer 37

always abnormal could be biliary atresia or hepatitis

Question 38

what is biliary atresia?

Answer 38

-a rare disorder causing obstructive jaundice which is fatal if left untreated

Question 39

how do patients with biliary atresia present?

Answer 39

- usually have pale clay coloured wstool - dark urine - jaundiced

Question 40

what is the treatment for biliary atresia?

Answer 40

-surgery with a Kasai portoenterostomy before 3 months of age

Question 41

what is the success of the biliary atresia surgery directly related to?

Answer 41

-age of operation <10 weeks= better chance of bile flow and reduced need for liver transplant

Question 42

what is the most common causes of unconjugated hyperbilirubinaemia?

Answer 42

- hypothyroidism (most common) | - breast milk jaundice

Question 43

what is done to detect hypothyroidism that causes unconjugated hyperbilirubinaemia early?

Answer 43

babies are screened for hypothyroidism

Question 44

what is the treatment for jaundice?

Answer 44

- treat underlying cause if present - adequate enteral feeding/hydration - if breast feeding is not established then top up feeds with expresed breast milk is best - sometimes supplementation with formula will be needed - occasionally some tube feeding will be required and for seriously unwell babies intravenous fluids - phototherapy (blue-green range light, make sure eye protection) - rarely must do an exchange transfusion (usually required for babies with Haemolytic disease) - IV immunoglobulin (used when bilirubin is increasing even in phototherapy)

Question 45

what treatment is often required to treat jaundice in babies with haemolytic disease?

Answer 45

-exchange transfusion

Question 46

what is normal weight loss in neonates?

Answer 46

up to 10%