Jaundice Flashcards
Liver functions?
- Factory: produces albumin, clotting factors
- Absorption of food we eat
- Acts as storage facility for glycogen
- Metabolism and excretion of toxic products of body
What are common LFTs and what do they tell us?
- Total bilirubin
- Split bilirubin: if it is unconjugated or conjugated
- ALT/AST: Elevated in hepatocellular damage (“hepatitis”)
- Alk phosphotase
- In children: alkalin phosphatase is ignored!!! Because released in bone growth, so pay more attention to GGT
- GGT
What tests can actually tell us how the liver is functioning??
- Coagulation
- Prothrombin time (PT)/INR
- APTT
- Albumin
- Bilirubin
- (Blood glucose)
- (Ammonia)
How does liver disease present in children?
-
JAUNDICE = most obvious in sclera
- Usually visible when total bilirubin >40-50 umol/l
- Incidental finding on blood test
- SSx of chronic liver disease
- same as adult but plus growth failure
Outline bilirubin metabolism:
What are the important features of conjugated and unconjugated bilirum?
- Process of RBC breakdown first occurs throughout body
- Then transported to liver where becomes conjugated bilirubin
- Unconjugated is water INSOLUBLE so cannot be directly secreted by kidneys, but is fat soluble
- Conjugated is water soluble so can get out of body
What areas of bilirubin metabolism correspond to different types of jaundice?
- Post hepatic: blockage stopping conjugated bilirubin from leaving liver
How is jaundice classified by age for infants? What are causes for each classification?
- Early <24hr old
- ALWAYS pathological
- Sepsis and haemolysis
- Intermediate 1-14 days
- Physiological, Breast milk, Sepsis, Haemolysis
- Prolonged >2wks old
- Extrahepatic obstruction, Neonatal hepatitis, Hypothyroidism, Breast milk
What are the causes of “physiological” jaundice?
- Shorter RBC life span in infants (80-90 days)
- Relative polycythaemia (Hb is raised 180-200 – start breaking down loads of RBCs resulting in loads of unconjugated red cells)
- Relative immaturity of liver function
- Unconjugated jaundice - because of overproduction and breakdown of RBC’s
- Develops after first day of life
What is breast milk jaundice?
- The prolongation of physiological jaundice
- Unconjugated
- Unsure why this happens
What are other causes of Early/Intermediate Unconjugated infant jaundice?
- Sepsis: causes haemolysis
- Haemolysis
- ABO incompatability
- Rhesus disease
- Bruising/cephalhaematoma from birth trauma
- Red cell membrane defects (e.g. spherocytosis)
- Red cell enzyme defects (e.g. G6PD)
- Abnormal conjugation
- Gilbert’s: mild and common
- Crigler-Najjar syndrome – v. rare, severe – cannot convert unconj to conjugated
What do we therefore investigate for in early/intermediate jaundice?
- Sepsis: urine and bloods
- Haemolysis: Blood group, clinical examination, blood film, G6DP assay
- Abnormal conjugation: genotype and phenotype
What is an important (unique to paeds) complication of unconjugated jaundice?
Kernicterus
- As unconjugated is fat soluble it can cross BBB
- Neurotoxic and deposits in brain
- Early signs – encephalopathy – poor feeding, lethargy, seizures
- Late consequences – severe choreoathetoid cerebral palsy, learning difficulties, sensorineural deafness
Rx for unconjugated jaundice?
- Visible light (450nm wavelength) (not UV) converts bilirubin to water soluble isomer (photoisomerisation)
- Threshold for phototherapy in infants guided by charts
Definition of prolonged jaundice?
- Jaundice that is persisting for more than 2 wks (3wks for preterm infants)
- This always requires further investigation.
Causes of prolonged jaundice?
Conjugated
- Anatomical (biliary obstruction)
- Neonatal hepatitis
Unconjugated
- Hypothyroidism
- Breast milk
