The Jaundiced Child

Question 1

What is jaundice in children?

Answer 1

Jaundice is the yellow appearance of the skin and mucous membranes due to bilirubin deposits.

Question 2

What causes jaundice in children?

Answer 2

Jaundice can be caused by:
1. Pre-hepatic increased bilirubin production
2. Hepatic metabolic dysfunction
3. Post-hepatic obstruction

Question 3

What are pre-hepatic causes of jaundice?

Answer 3

Pre-hepatic causes include increased bilirubin production due to haemolysis or haemorrhage.

Question 4

What are hepatic causes of jaundice?

Answer 4

Hepatic causes include impaired hepatocyte uptake of bilirubin, impaired conjugation of bilirubin, or reduced secretion of bilirubin from liver cells.

Question 5

What are post-hepatic causes of jaundice?

Answer 5

Post-hepatic causes involve obstruction of intra- or extra-hepatic bile ducts, impairing the excretion of bilirubin.

Question 6

What is “surgical jaundice”?

Answer 6

“Surgical jaundice” refers to obstructive jaundice caused by post-hepatic (usually extra-hepatic) obstruction, which is often treatable with surgical interventions.

Question 7

What happens to old red blood cells in the body?

Answer 7

Old red blood cells are broken down in the spleen and bone marrow, releasing haem, which is further broken down into biliverdin and then into fat-soluble bilirubin.

Question 8

What are the properties of unconjugated bilirubin?

Answer 8

Unconjugated bilirubin is fat-soluble and has antioxidant properties. It is reversibly bound to albumin and transported to the liver.

Question 9

What happens to unconjugated bilirubin in the liver?

Answer 9

In the liver, unconjugated bilirubin is conjugated by the enzyme UDP-glucuronyl transferase, which binds it to glucuronic acid, making it water-soluble.

Question 10

How is conjugated bilirubin excreted from the liver?

Answer 10

Conjugated bilirubin is excreted via the biliary tree into the duodenum.

Question 11

Why is bile green in color?

Answer 11

Bile is green due to the presence of conjugated bilirubin, which gives bile its typical brown-green color.

Question 12

What is the role of conjugated bile acids in digestion?

Answer 12

Conjugated bile acids (bile salts) are excreted by the liver into bile, where they help digest fats by emulsifying them into tiny absorbable particles called micelles.

Question 13

What causes jaundice and pruritus (itchiness) in bile duct obstruction?

Answer 13

Bile duct obstruction leads to the accumulation of conjugated bilirubin, causing jaundice, and the accumulation of bile salts under the skin, causing pruritus (itchiness)

Question 14

Why is stool brown in color?

Answer 14

Conjugated bilirubin passes through the small bowel into the colon, where it is deconjugated by bacteria into stercobilinogen. Stercobilinogen is oxidized into stercobilin and urobilin, which have a brown color.

Question 15

Why are neonate and infant stools yellow instead of brown?

Answer 15

Neonates and infants have lower bacterial levels in their guts, which results in their stools being yellow rather than brown.

Question 16

Why is urine yellow in color?

Answer 16

A small amount of stercobilinogen is reabsorbed into the blood circulation as urobilinogen. Urobilinogen is converted to urobilin, which gives urine its yellow color.

Question 17

How does impaired excretion of conjugated bilirubin affect urine color?

Answer 17

If conjugated bilirubin is not properly excreted, some leaks out of the hepatocytes into the serum, and because it is water-soluble, it is excreted in the urine. This causes the urine to become darker or amber in color.

Question 18

What are the two types of bilirubin usually measured in laboratories?

Answer 18

Laboratories typically measure total bilirubin levels and “direct bilirubin,” which includes conjugated and albumin-bound bilirubin.

Question 19

How is unconjugated bilirubin level calculated?

Answer 19

Unconjugated bilirubin (UB) is calculated as the difference between total bilirubin (TB) and direct bilirubin (DB). (UB = TB - DB)

Question 20

At what bilirubin level is yellow discoloration of the sclera typically seen?

Answer 20

Yellow discoloration of the sclera is usually seen at bilirubin levels of about 34 to 51 µmol/L.

Question 21

At what bilirubin level does jaundice of the face typically appear?

Answer 21

Jaundice of the face is usually seen at bilirubin levels of 68-86 µmol/L.

Question 22

How does jaundice typically progress in the body?

Answer 22

Jaundice usually progresses from the face down towards the feet in a craniocaudal direction.

Question 23

How common is neonatal jaundice?

Answer 23

Half of neonates will be visibly jaundiced in the first week after birth, with unconjugated hyperbilirubinaemia reported in 65% of term and 80% of preterm neonates.

Question 24

What are the causes of physiological jaundice in neonates?

Answer 24

Causes include:
1. High bilirubin production due to the breakdown of short-lived fetal haemoglobin (HbF).
2. Liver immaturity, leading to impaired enzymatic conjugation of bilirubin.
3. Raised enterohepatic recirculation, where β-glucuronidase deconjugates bilirubin, allowing its re-absorption into the bloodstream.

Question 25

Why is the blood-brain barrier a concern in neonates with jaundice?

Answer 25

The blood-brain barrier is immature in neonates, allowing free unconjugated bilirubin to cross into the brain and potentially cause brain damage.

Question 26

What is kernicterus

Answer 26

Kernicterus is brain damage caused by the deposition of unconjugated bilirubin in the basal ganglia, due to inadequate bilirubin conjugation from liver immaturity.

Question 27

How is unconjugated hyperbilirubinaemia treated in neonates?

Answer 27

Unconjugated hyperbilirubinaemia is treated with phototherapy, which uses UV light to cause bilirubin isomerization, making it water-soluble and allowing excretion in bile.

Question 28

Can phototherapy treat conjugated hyperbilirubinaemia?

Answer 28

No, phototherapy has no role in treating conjugated hyperbilirubinaemia

Question 29

What type of jaundice is most common in early neonatal jaundice (<72h after birth)?

Answer 29

Early neonatal jaundice is almost always unconjugated.

Question 30

Why might exchange transfusion be needed in early neonatal jaundice?

Answer 30

Exchange transfusion may be required to prevent kernicterus in cases of severe unconjugated hyperbilirubinaemia.

Question 31

What investigations should be done in cases of early neonatal jaundice?

Answer 31

Investigate for haemolysis using: 1. Heinz bodies on blood film 2. Raised reticulocyte count and LDH 3. Coombs test for immune-mediated haemolysis

Question 32

What are some common causes of haemolysis in early neonatal jaundice?

Answer 32

Common causes include: 1. Rhesus iso-immunisation 2. ABO incompatibility 3. G6-PD enzyme deficiency

Question 33

What congenital infections should be excluded in early neonatal jaundice?

Answer 33

Exclude infections due to “TORCHES” organisms, which include: 1. Toxoplasmosis 2. Rubella 3. Cytomegalovirus 4. Herpes simplex 5. HIV 6. Syphilis

Question 34

What is breast-feeding jaundice and what causes it?

Answer 34

Breast-feeding jaundice occurs due to inadequate caloric intake, leading to exaggerated physiological jaundice, especially in premature infants. Poor latching increases intestinal transit time and enterohepatic circulation, causing reabsorption of unconjugated bilirubin.

Question 35

Why do neonates have enhanced enterohepatic reabsorption of bilirubin?

Answer 35

Neonates produce β-glucuronidase in their intestinal brush borders, which deconjugates bilirubin, allowing it to be reabsorbed into circulation and contributing to enhanced enterohepatic circulation.

Question 36

When does breast-milk jaundice typically occur?

Answer 36

Breast-milk jaundice typically occurs from 1 week up to 3-4 months after birth.

Question 37

What is intermediate neonatal jaundice?

Answer 37

Intermediate neonatal jaundice occurs between 72 hours and 2 weeks after birth and is usually physiological. It may also be associated with conditions like sepsis, haemolysis, or metabolic disorders.

Question 38

What are some causes to consider in intermediate neonatal jaundice?

Answer 38

Causes to consider include: 1. Sepsis 2. Haemolysis (e.g., bruising from birth trauma like cephalhaematoma, or polycythaemia) 3. Metabolic causes like Crigler-Najjar syndrome and Gilbert syndrome

Question 39

What is Crigler-Najjar syndrome?

Answer 39

Crigler-Najjar syndrome is a genetic disorder where there is absent UDP-glucuronyl transferase, impairing bilirubin conjugation and leading to jaundice.

Question 40

What is Gilbert syndrome?

Answer 40

Gilbert syndrome is a condition with impaired UDP-glucuronyl transferase activity, leading to jaundice, especially during stress or starvation. It affects about 5% of the population.

Question 41

What is considered late or prolonged neonatal jaundice?

Answer 41

Late or prolonged neonatal jaundice is jaundice that persists or presents after 14 days postnatally in term infants.

Question 42

What should always be checked when diagnosing late/prolonged neonatal jaundice?

Answer 42

It is important to determine whether the jaundice is unconjugated or conjugated.

Question 43

What are some causes of unconjugated late/prolonged neonatal jaundice?

Answer 43

Causes include: 1. Physiological jaundice (e.g., breast-milk jaundice) 2. Infection (e.g., TORCH organisms, sepsis) 3. Metabolic disorders (e.g., hypothyroidism)

Question 44

How is breast-milk jaundice diagnosed and treated?

Answer 44

Diagnosis is confirmed by observing a response in bilirubin levels to temporarily stopping breastmilk. Treatment is reassurance, and breastfeeds should be continued.

Question 45

What are the causes of conjugated late/prolonged neonatal jaundice?

Answer 45

Causes include: 1. Infection (e.g., neonatal hepatitis) 2. Extra-hepatic biliary obstruction (e.g., biliary atresia, choledochal cyst, biliary hypoplasia in Alagille syndrome) 3. Metabolic disorders (e.g., alpha-1-antitrypsin deficiency, tyrosinaemia, galactosaemia)

Question 46

What are some causes of extra-hepatic biliary obstruction leading to conjugated jaundice?

Answer 46

Causes include: 1. Biliary atresia 2. Choledochal cyst 3. Biliary hypoplasia (e.g., in Alagille syndrome) 4. Biliary sludge/gallstones (e.g., in babies on parenteral nutrition or with cystic fibrosis)

Question 47

What are some metabolic disorders associated with conjugated jaundice?

Answer 47

Metabolic disorders include: 1. Alpha-1-antitrypsin deficiency 2. Tyrosinaemia 3. Galactosaemia

Question 48

What causes unconjugated hyperbilirubinemia in pathological jaundice?

Answer 48

Causes include: • Increased haem breakdown • Decreased hepatic uptake of bilirubin • Decreased hepatic conjugation (due to low enzyme levels) • Increased enterohepatic circulation

Question 49

What causes conjugated hyperbilirubinemia in pathological jaundice?

Answer 49

Causes include: • Intra-hepatic or extra-hepatic bile duct obstruction • Hepatocyte dysfunction (impaired secretion)

Question 50

What is the age of presentation for unconjugated hyperbilirubinemia?

Answer 50

It presents before 3 days or after 10-14 days in term infants, and after 21 days in preterm infants. Slightly raised levels are normal in breastfed infants up to 28 days.

Question 51

What is the age of presentation for conjugated hyperbilirubinemia?

Answer 51

It typically presents after 14 days in term infants or after 21 days in preterm infants.

Question 52

What are the clinical features of unconjugated hyperbilirubinemia?

Answer 52

Clinical features include yellow-orange skin color.

Question 53

What are the clinical features of conjugated hyperbilirubinemia?

Answer 53

Clinical features include yellow-green skin color, pale stools, dark urine, and hepatosplenomegaly, especially if associated with an infectious cause or portal hypertension. Late presentation may show a hard, small, shrunken cirrhotic liver.

Question 54

What are the liver enzyme findings in unconjugated hyperbilirubinemia?

Answer 54

Raised total and unconjugated bilirubin fraction. Cellular and ductal enzymes may be normal, or cellular enzymes may be predominantly raised.

Question 55

What are the liver enzyme findings in conjugated hyperbilirubinemia?

Answer 55

Raised total and conjugated bilirubin fraction. Ductal enzymes (ALP, GGT) are usually much more raised than cellular enzymes (AST, ALT) in obstructive jaundice.