The Jaundiced Child Flashcards
What is jaundice in children?
Jaundice is the yellow appearance of the skin and mucous membranes due to bilirubin deposits.
What causes jaundice in children?
Jaundice can be caused by:
1. Pre-hepatic increased bilirubin production
2. Hepatic metabolic dysfunction
3. Post-hepatic obstruction
What are pre-hepatic causes of jaundice?
Pre-hepatic causes include increased bilirubin production due to haemolysis or haemorrhage.
What are hepatic causes of jaundice?
Hepatic causes include impaired hepatocyte uptake of bilirubin, impaired conjugation of bilirubin, or reduced secretion of bilirubin from liver cells.
What are post-hepatic causes of jaundice?
Post-hepatic causes involve obstruction of intra- or extra-hepatic bile ducts, impairing the excretion of bilirubin.
What is “surgical jaundice”?
“Surgical jaundice” refers to obstructive jaundice caused by post-hepatic (usually extra-hepatic) obstruction, which is often treatable with surgical interventions.
What happens to old red blood cells in the body?
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.
What are the properties of unconjugated bilirubin?
Unconjugated bilirubin is fat-soluble and has antioxidant properties. It is reversibly bound to albumin and transported to the liver.
What happens to unconjugated bilirubin in the liver?
In the liver, unconjugated bilirubin is conjugated by the enzyme UDP-glucuronyl transferase, which binds it to glucuronic acid, making it water-soluble.
How is conjugated bilirubin excreted from the liver?
Conjugated bilirubin is excreted via the biliary tree into the duodenum.
Why is bile green in color?
Bile is green due to the presence of conjugated bilirubin, which gives bile its typical brown-green color.
What is the role of conjugated bile acids in digestion?
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.
What causes jaundice and pruritus (itchiness) in bile duct obstruction?
Bile duct obstruction leads to the accumulation of conjugated bilirubin, causing jaundice, and the accumulation of bile salts under the skin, causing pruritus (itchiness)
Why is stool brown in color?
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.
Why are neonate and infant stools yellow instead of brown?
Neonates and infants have lower bacterial levels in their guts, which results in their stools being yellow rather than brown.
Why is urine yellow in color?
A small amount of stercobilinogen is reabsorbed into the blood circulation as urobilinogen. Urobilinogen is converted to urobilin, which gives urine its yellow color.
How does impaired excretion of conjugated bilirubin affect urine color?
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.
What are the two types of bilirubin usually measured in laboratories?
Laboratories typically measure total bilirubin levels and “direct bilirubin,” which includes conjugated and albumin-bound bilirubin.
How is unconjugated bilirubin level calculated?
Unconjugated bilirubin (UB) is calculated as the difference between total bilirubin (TB) and direct bilirubin (DB). (UB = TB - DB)
At what bilirubin level is yellow discoloration of the sclera typically seen?
Yellow discoloration of the sclera is usually seen at bilirubin levels of about 34 to 51 µmol/L.
At what bilirubin level does jaundice of the face typically appear?
Jaundice of the face is usually seen at bilirubin levels of 68-86 µmol/L.
How does jaundice typically progress in the body?
Jaundice usually progresses from the face down towards the feet in a craniocaudal direction.
How common is neonatal jaundice?
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.
What are the causes of physiological jaundice in neonates?
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.
Why is the blood-brain barrier a concern in neonates with jaundice?
The blood-brain barrier is immature in neonates, allowing free unconjugated bilirubin to cross into the brain and potentially cause brain damage.
What is kernicterus
Kernicterus is brain damage caused by the deposition of unconjugated bilirubin in the basal ganglia, due to inadequate bilirubin conjugation from liver immaturity.
How is unconjugated hyperbilirubinaemia treated in neonates?
Unconjugated hyperbilirubinaemia is treated with phototherapy, which uses UV light to cause bilirubin isomerization, making it water-soluble and allowing excretion in bile.
Can phototherapy treat conjugated hyperbilirubinaemia?
No, phototherapy has no role in treating conjugated hyperbilirubinaemia
What type of jaundice is most common in early neonatal jaundice (<72h after birth)?
Early neonatal jaundice is almost always unconjugated.
Why might exchange transfusion be needed in early neonatal jaundice?
Exchange transfusion may be required to prevent kernicterus in cases of severe unconjugated hyperbilirubinaemia.
What investigations should be done in cases of early neonatal jaundice?
Investigate for haemolysis using:
1. Heinz bodies on blood film
2. Raised reticulocyte count and LDH
3. Coombs test for immune-mediated haemolysis
What are some common causes of haemolysis in early neonatal jaundice?
Common causes include:
1. Rhesus iso-immunisation
2. ABO incompatibility
3. G6-PD enzyme deficiency
What congenital infections should be excluded in early neonatal jaundice?
Exclude infections due to “TORCHES” organisms, which include:
1. Toxoplasmosis
2. Rubella
3. Cytomegalovirus
4. Herpes simplex
5. HIV
6. Syphilis
What is breast-feeding jaundice and what causes it?
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.
Why do neonates have enhanced enterohepatic reabsorption of bilirubin?
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.
When does breast-milk jaundice typically occur?
Breast-milk jaundice typically occurs from 1 week up to 3-4 months after birth.
What is intermediate neonatal jaundice?
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.
What are some causes to consider in intermediate neonatal jaundice?
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
What is Crigler-Najjar syndrome?
Crigler-Najjar syndrome is a genetic disorder where there is absent UDP-glucuronyl transferase, impairing bilirubin conjugation and leading to jaundice.
What is Gilbert syndrome?
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.
What is considered late or prolonged neonatal jaundice?
Late or prolonged neonatal jaundice is jaundice that persists or presents after 14 days postnatally in term infants.
What should always be checked when diagnosing late/prolonged neonatal jaundice?
It is important to determine whether the jaundice is unconjugated or conjugated.
What are some causes of unconjugated late/prolonged neonatal jaundice?
Causes include:
1. Physiological jaundice (e.g., breast-milk jaundice)
2. Infection (e.g., TORCH organisms, sepsis)
3. Metabolic disorders (e.g., hypothyroidism)
How is breast-milk jaundice diagnosed and treated?
Diagnosis is confirmed by observing a response in bilirubin levels to temporarily stopping breastmilk. Treatment is reassurance, and breastfeeds should be continued.
What are the causes of conjugated late/prolonged neonatal jaundice?
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)
What are some causes of extra-hepatic biliary obstruction leading to conjugated jaundice?
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)
What are some metabolic disorders associated with conjugated jaundice?
Metabolic disorders include:
1. Alpha-1-antitrypsin deficiency
2. Tyrosinaemia
3. Galactosaemia
What causes unconjugated hyperbilirubinemia in pathological jaundice?
Causes include:
• Increased haem breakdown
• Decreased hepatic uptake of bilirubin
• Decreased hepatic conjugation (due to low enzyme levels)
• Increased enterohepatic circulation
What causes conjugated hyperbilirubinemia in pathological jaundice?
Causes include:
• Intra-hepatic or extra-hepatic bile duct obstruction
• Hepatocyte dysfunction (impaired secretion)
What is the age of presentation for unconjugated hyperbilirubinemia?
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.
What is the age of presentation for conjugated hyperbilirubinemia?
It typically presents after 14 days in term infants or after 21 days in preterm infants.
What are the clinical features of unconjugated hyperbilirubinemia?
Clinical features include yellow-orange skin color.
What are the clinical features of conjugated hyperbilirubinemia?
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.
What are the liver enzyme findings in unconjugated hyperbilirubinemia?
Raised total and unconjugated bilirubin fraction. Cellular and ductal enzymes may be normal, or cellular enzymes may be predominantly raised.
What are the liver enzyme findings in conjugated hyperbilirubinemia?
Raised total and conjugated bilirubin fraction. Ductal enzymes (ALP, GGT) are usually much more raised than cellular enzymes (AST, ALT) in obstructive jaundice.
