Approach to the Jaundiced Baby Flashcards
Liver functions
Production of proteins essential for day-to-day life, particularly albumin, and clotting factors
Metabolism - absorption, digestion and processing of fat, carbohydrate and protein
Role in storage of fat, carbohydrate and protein, particularly glycogen
Filter of toxic metabolites (and drugs) - processed and excreted
Liver function tests
Bilirubin
- Total bilirubin
- Split bilirubin; direct (conjugated) and indirect (unconjugated)
ALT/AST
(alanine aminotransferase/aspartate aminotransferase)
- elevated in hepatocellular damage
Alkaline phosphatase
- elevated in biliary disease, useful in adults but not as helpful in paediatrics
Gamma glutamyl transferase (GGT)
- elevated in biliary disease
These are markers of liver damage rather than liver function
Tests to assess liver function (rather than liver damage)
Coagulation - prothrombin time (PT)/INR, APTT Albumin Bilirubin Blood glucose Ammonia
Clinical manifestations of paediatric liver disease
Jaundice (!!!)
Incidental finding of abnormal blood test
Symptoms/signs of chronic liver disease are rarely seen
Signs of liver disease in children
Same manifestations as in adults plus growth failure
- jaundice
- cholestasis
- spider naevi
- muscle wasting
- splenomegaly
- ascites
- epistaxis
etc.
What is jaundice and when is it most obvious?
Jaundice is the yellow discolouration of skin and tissues due to accumulation of bilirubin
Usually most obvious in sclera, usually visible when total bilirubin > 40-50umol/l
Describe bilirubin metabolism
Starts in erythrocytes
Erythrocytes broken down to haem, breakdown product is biliverdin
Biliverdin is acted on by biliverdin reductase in all tissues to form unconjugated bilirubin
Unconjugated bilirubin is albumin-bound and transported to the liver
In the liver, conjugation occurs by UDP glucuronyl transferase
Conjugated bilirubin present in bile which is transported to small intestine
In small intestine, bilirubin is converted to urobilinogen which is either transported back to the liver and recycled, excreted by the kidneys or converted to stercobilin which is excreted in stool
What kind if bilirubin is most commonly present in pre-hepatic, intra-hepatic and post-hepatic jaundice?
Pre-hepatic most commonly unconjugated bilirubin
Intra-hepatic most commonly mixed i.e. unconjugated and conjugated bilirubin
Post-hepatic most commonly conjugated bilirubin
What is the classification of neonatal jaundice?
Classification by age
Early
- < 24 hours old
- always pathological
- e.g. due to haemolysis or sepsis
Intermediated
- 24 hours to 2 weeks old
- can be a normal physiological process due to breast milk
- may be sepsis or haemolysis
Prolonged
- > 2 weeks old
- caused by extra-hepatic obstruction, neonatal hepatitis, hypothyroidism or breast milk
Features of physiological jaundice
Shorter RBC lifespan in infants (80-90 days) Relative polycythaemia Relative immaturity of liver function Unconjugated jaundice Develops after first day of life
Features of breast milk jaundice
Exact reason for prolongation of jaundice in breastfed infants is unclear
Unconjugated jaundice
Can persist up to 12 weeks
Causes of early/intermediate unconjugated infant jaundice
Sepsis
Haemolysis
- ABO incompatibility
- Rhesus disease
- bruising/cephalhaematoma
- red cell membrane defects e.g. spherocytosis
- red cell enzyme defects e.g. G6DP
Abnormal conjugation
- Gilbert’s disease (common, mild)
- Crigler-Najjar syndrome (very rare, severe)
Investigations for jaundice when suspecting sepsis, haemolysis or abnormal conjugation
Sepsis - urine and blood cultures, TORCH screen
Haemolysis
- blood group
- DCT (ABO incompatibility and Rhesus)
- clinical examination (bruising)
- blood film (RBC membrane defects)
- G6DP (RBC enzyme defects)
Abnormal conjugation - genotype/phenotype
Features of Kernicterus
Complication of neonatal jaundice
Unconjugated bilirubin is fat-soluble (water-insoluble) so can cross blood brain barrier
Neurotoxic, deposits in brain
Early signs - encephalopathy, poor feeding, lethargy, seizures
Later consequences - severe choreoathetoid cerebral palsy, learning difficulties, sensorineural deafness
Use of phototherapy in jaundice treatment
Treatment for unconjugated jaundice
Visible light (450nm wavelength, not UV) used
Converts bilirubin to water soluble isomer (photoisomerisation)
