Approach to the Yellow Baby Flashcards
What is included in LFTs?
LIVER DAMAGE TESTS
Bilirubin
ALT/AST (alanine aminotransferase/aspartate aminotransferase)
Alkaline phosphatase
Gamma glutamyl transferase (GGT)
What bilirubin measurements are taken?
Total bilirubin
“Split” bilirubin – Direct (conjugated) + Indirect (unconjugated)
When is ALT/AST elevated?
Elevated in hepatocellular damage (“hepatitis”)
When are alkaline phosphatase and gamma glutamyl transferase (GGT) elevated?
Biliary disease
How might liver FUNCTION be tested?
Coagulation
Albumin
Bilirubin
(Blood glucose)
(Ammonia)
What measurements are used to assess coagulation?
Prothrombin time (PT)/INR
APTT (activated partial thromboplastin time)
How does paediatric liver disease clinically manifest?
JAUNDICE
Incidental finding of abnormal blood test
Symptoms/signs of chronic liver disease
Where is jaundice most obvious?
Sclera
When does jaundice become visible?
Total bilirubin >40-50 umol/l
What is diagnosis of infant jaundice dependent on?
Understanding bilirubin metabolism
Age of the infant
Where in bilirubin metabolism does pre-hepatic jaundice occur?
Post-mature erythrocytes –> Unconjugated bilirubin
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Where does intrahepatic jaundice occur?
Unconjugated –> conjugated bilirubin (at liver)
Where does post-hepatic jaundice occur?
CHOLESTASIS
Conjugated bilirubin combined with bile in the small intestine to form urobilirubin
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What are the classifications of infant jaundice?
Early (<24 hours old)
Intermediate (24hrs – 2 weeks)
Prolonged (>2 weeks)
What are the causes of early infant jaundice?
ALWAYS PATHOLOGICAL
Haemolysis
Sepsis
What are the causes of intermediate infant jaundice?
Physiological, Breast milk, Sepsis, Haemolysis
What are the causes of prolonged infant jaundice?
Extrahepatic obstruction, Neonatal hepatitis, Hypothyroidism, Breast milk
What are the causes of prolonged infant jaundice?
Extrahepatic obstruction, Neonatal hepatitis, Hypothyroidism, Breast milk
What is physiological jaundice?
Shorter RBC life span in infants (80-90 days)
Relative polycythaemia
Relative immaturity of liver function
Unconjugated jaundice
Develops after first day of life
What is breast milk jaundice?
Exact reason for prolongation of jaundice in breastfed infants unclear
- Inhibition of UDP by progesterone metabolite?
- Increased enterohepatic circulation?
Unconjugated jaundice
Can persist up to 12 weeks
What is the cause of kernicterus?
Unconjugatedbilirubin is fat-soluble (water insoluble) so can cross blood-brain barrier and become neurotoxic, leaving deposits in the brain
What are the early signs of kericterus?
Encephalopathy – poor feeding, lethargy, seizures
What are the late consequences of kericterus?
Severe choreoathetoidcerebral palsy
Learning difficulties
Sensorineural deafness
What is phototherapy?
- Treatment for unconjugated jaundice
- Visible light (450nm wavelength) (not UV) converts bilirubin to water soluble isomer (photoisomerisation)
- Threshold for phototherapy in infants guided by charts
What are some other causes or early/intermediate unconjugated infant jaundice?
Sepsis
Haemolysis
Abnormal conjugation
What tests do you do to confirn jaundice sepsis?
Urine + blood cultures, TORCH screen
What are the causes of haemolysis jaundice and how is each tested for?
- ABO incompatibility (Blood group, DCT)
- Rhesus disease (Blood group, DCT)
- Bruising/cephalhaematoma (clinical examination)
- Red cell membrane defects (e.g. spherocytosis) (Blood film)
- Red cell enzyme defects (e.g. G6PD) (G6PD assay)
DCT - direct Coombs test
What are the causes of “abnormal conjugaton” jaundice and how are they tested for?
- Gilbert’s disease (genotype/phenotype)
- Crigler-Najjarsyndrome (genotype/phenotype)
What is the minimum prolonged jaundice duration for pre-term infants?
3 weeks
Of the 4 types of prolonged infant jaunidce, which are conjugated and which are unconjugated?
Conjugated:
- Anatomical (biliary obstruction)
- Neonatal hepatitis
Unconjugated:
- Hypothyroidism
- Breast-milk jaundice
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What are the 3 key messages for prolonged infant jaundice?
- Conjugated jaundice in infants is always abnormal and always requires further investigation
- The most important test in prolonged jaundice is a “split” bilirubin
- Always assess stool colour in infants with prolonged jaundice
- Assessment of prolonged infant jaundice is primarily targeted at diagnosing patients with biliary atresia early
What are the 3 causes of bilary obstruction in infants?
- Biliary atresia
- Choledochal cyst
- Alagille syndrome
How does biliary atresia and choledochal cysts present?
Conjugated jaundice
Pale stools
How does Alagille syndrome present?
•Intrahepatic cholestasis, dysmorphism, congenital cardiac disease
What is biliary atresia?
- Congenital fibro-inflammatory disease of bile ducts leading to destruction of extra-hepatic bile ducts
- Presents with prolonged, conjugated jaundice
- Pale stools, dark urine
- Progression to liver failure if not identified and treated
- Timely diagnosis critical as time to treatment determines prognosis
- Most common indication for liver transplantation in children
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What is Kasai portoenterostomy?
Biliary atresia treatment
Success rate diminishes rapidly with age
Best results if performed before 60 days (<9 weeks)
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How is biliary atresia tetsed for?
Split bilirubin
Stool colour
Ultrasound
Liver biopsy
How are coledochal cysts and and Alagille syndrome tested for?
- Choledochal cyst - split bilirubin, stool colour, ultrasound)
- Alagille syndrome - dysmorphism, genotype
What are the causes of neonatal hepatitis (conjugated jaundice) and now are they tested for?
- Alpha-1-antitrypsin deficiency (phenotype/level)
- Galactosaemia (GAL-1-PUT)
- Tyrosinaemia (amino acid profile)
- Urea cycle defects (ammonia)
- Haemochromatosis (iron studies, liver biopsy)
- Glycogen storage disorders (biopsy)
- Hypothyroidism (TFTs)
- Viral hepatitis (serology, PCR)
- Parenteral nutrition (history)
Summary
- Always ask about stool colour
- Most important test is a split bilirubin to differentiate unconjugated from conjugated jaundice
- Conjugated jaundice always requires further investigation and should be considered biliary atresia until proven otherwise