Approach to the Yellow Baby Flashcards by Lucy McLean

What is included in LFTs?

LIVER DAMAGE TESTS

Bilirubin

ALT/AST (alanine aminotransferase/aspartate aminotransferase)

Alkaline phosphatase

Gamma glutamyl transferase (GGT)

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What bilirubin measurements are taken?

Total bilirubin

“Split” bilirubin – Direct (conjugated) + Indirect (unconjugated)

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When is ALT/AST elevated?

Elevated in hepatocellular damage (“hepatitis”)

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When are alkaline phosphatase and gamma glutamyl transferase (GGT) elevated?

Biliary disease

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How might liver FUNCTION be tested?

Coagulation

Albumin

Bilirubin

(Blood glucose)

(Ammonia)

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What measurements are used to assess coagulation?

Prothrombin time (PT)/INR

APTT (activated partial thromboplastin time)

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How does paediatric liver disease clinically manifest?

JAUNDICE

Incidental finding of abnormal blood test

Symptoms/signs of chronic liver disease

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Where is jaundice most obvious?

Sclera

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When does jaundice become visible?

Total bilirubin >40-50 umol/l

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What is diagnosis of infant jaundice dependent on?

Understanding bilirubin metabolism

Age of the infant

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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)

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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)

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What are the causes of early infant jaundice?

ALWAYS PATHOLOGICAL

Haemolysis

Sepsis

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What are the causes of intermediate infant jaundice?

Physiological, Breast milk, Sepsis, Haemolysis

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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

What are the 3 key messages for prolonged infant jaundice?

1. Conjugated jaundice in infants is always abnormal and always requires further investigation * The most important test in prolonged jaundice is a “split” bilirubin 2. Always assess stool colour in infants with prolonged jaundice 3. 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

What is Kasai portoenterostomy?

Biliary atresia treatment Success rate diminishes rapidly with age Best results if performed before 60 days (\<9 weeks)

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