Paediatric gastroenterology

Question 1

Know the functions of the liver and the clinical manifestations of paediatric liver disease

Be aware of the biochemical markers used in the assessment of liver disease

Describe the causes of unconjugated and conjugated hyperbilirubinaemia and prolonged neonatal jaundice (including biliary atresia)

Answer 1

.

Question 2

Functions of the liver

Answer 2

Stores excess glucose as glycogen (later can be converted back for energy)

Clearing the blood of drugs and other poisonous substances

Stores vitamins, fat, sugars and minerals and sends them around when needed

Conversion of poisonous ammonia to urea (to be excreted)

Produces bile which breaks down fats in the SI

Produce clotting factors

Produce cholesterol

Clearance of bilirubin

Question 3

Name the LFTs

+ which ones actually assess liver FUNCTION* (3)

Answer 3

Bilirubin* - total, “split” (direct (conjugated) + indirect (unconjugated))

ALT/AST (alanine aminotransferase/aspartate aminotransferase)

Alkaline phosphatase

Gamma glutamyl transferase (GGT)

Coagulation* - prothrombin time (PT)/INR, APTT

Albumin*

(Blood glucose)*
(Ammonia)*

Question 4

Which 2 LFTs are elevated in biliary disease

Answer 4

Alkaline phosphatase

Gamma glutamyl transferase (GGT)

Question 5

3 clinical manifestations of paediatric liver disease

Answer 5

JAUNDICE - COMMONEST

Incidental finding on abnormal blood test

Symptoms/signs of CLD + GROWTH FAILURE

Question 6

Jaundice = yellow discolouration of skin due to accumulation of bilirubin

It’s visible when total bilirubin > …

Answer 6

40-50 nanomol/l

Question 7

Describe the stages of bilirubin metabolism (7)

Answer 7

1. Old RBCs broken down by reticuloendothelial system into HAEM + globin
2. Haem further broken down into biliverdin by haem oxygenase
3. Biliverdin reductase breaks down biliverdin into UNCONJUGATED BILIRUBIN
4. This binds to albumin in the blood and transported to liver
5. Unconjugated bilirubin is conjugated by UDP glucuronyl transferase in the liver to form CONJUGATED BILIRUBIN
6. Most of the conjugated bilirubin is excreted out of the liver with bile into bile duct and out to the SI where it’s metabolised into UROBILINOGEN
7. Urobilinogen is oxidised into urobilin (excreted via kidneys in urine giving it yellow colour) or stercobilin (excreted in faeces giving it brown colour)
   TINY amounts of urobilinogen is reabsorbed into the enterohepatic circulation to be re-excreted in the bile

Question 8

Pre-hepatic jaundice is due to defects where in the process of bilirubin metabolism

Usual cause of pre-hepatic jaundice ?

Answer 8

Process of forming unconjugated bilirubin

Cause
-Increased release of haemoglobin from RBC (due to increased haemolysis) –> INCREASED CIRCULATING UNCONJUGATED BILIRUBIN

(so stages 1-3 in other flashcard)

Question 9

Intra-hepatic jaundice is due to defects where in the process of bilirubin metabolism

Causes of intra-hepatic jaundice? (2)

Answer 9

Defective conjugation of unconjugated bilirubin in the liver so defective excretion (unconjugated bilirubin excreted instead of conjugated)

Causes

• cholestasis
• intra-hepatic bile duct obstruction (PBC, PSC or tumours)

Question 10

Is intrahepatic jaundice a problem of conjugated or unconjuagted bilirubin

Answer 10

Both - as some bilirubin is probably still conjugated

Question 11

Post-hepatic jaundice is due to defects where in the process of bilirubin metabolism

Causes of post-hepatic jaundice? (3)

Answer 11

Defective transport of bilirubin out of the liver

Causes

• gallstones
• gallbladder disease
• extra-hepatic duct obstruction