3. Jaundice and its causes

Question 1

what is jaundice and what levels in the blood make it clinically apparent

Answer 1

yellowish discolouration of the skin, mucous membrane and sclera due to the accumulation of either unconjugated or conjugated bilirubin

50 micromoles per L

Question 2

what is the main difference between conjugated and unconjugated bilirubin

Answer 2

unconjugated bilirubin is formed from the breakdown of haemoglobin (not water soluble)

becomes conjugated by the liver and therefore becomes water soluble

Question 3

Excess conjugated hyperbilirrbuinemia causes what classical clinical findings

Answer 3

dark urine and pale stools

(can be further divided into obstructive or hepatocellular jaundice

Question 4

Tell me about bile
where is it stored
when is it released
what are the main components

Answer 4

stored and concentrated in the gallbladder
released in response to food (CCK) and vagal response to food
bile is mainly water (96%) and contains HCO3 and so is alkaline
bile also contains bile pigments which are haemoglobin breakdown products as well as bile salts which are derived from cholesterol

Question 5

in the hepatocyte what enzyme conjugates bilirubin with glucuronic acid

Answer 5

glucuronyl transferase

Question 6

What percentage of urobilinogen is excreted in the faces and so makes the faces dark

Answer 6

90%

Question 7

what percentage of urobilinogen is reabsorbed via the portal vein back into the hepatocyte and then the amount that goes into the blood makes the urine yellow

Answer 7

10% (80% goes back into hepatocyte and other 20% goes into the blood and excreted into bile)

Question 8

Name the broad categories of causes of jaundice

Answer 8

-haemolysis: increased levels of UB

• hepatic: associated with signs of liver failure and this could be either:
  a) obstructive: by blockage of flow of bile through bile ducts or intra/extrahepatic ducts
  b) hepatocellular: hepatocyte damage eg hepatitis or cirrhosis

Question 9

Name the common and uncommon causes of obstructive jaundice

Answer 9

Common
- gallstones (biliary colic and cholecystitis/cholangiitits)
- carcinoma of head of pancreas
uncommon
- Chronic pancreatitis
- sclerosing cholangitis (scarring of the smaller bile ducts)
- Cholangiocarcinoma (cancer of the bile duct)

Question 10

What does the urine and stools look like in someone with obstructive jaundice and why

Answer 10

increased conjugated bilirubin which makes the urine dark
no bilirubin is in the intestines therefore stools are pale
(Less bilirubin in stool means less stercobilinogen, therefore urinary urobilinogen is absent)

Question 11

Name some causes of hepatocellular jaundice

Answer 11

Common
- alcoholic hepatitis
- cirrhosis (could be secondary to alcohol or steatohepatitis)
- viral hepatitis
- drug induced (eg paracetamol overdose)
- non-alcoholic fatty liver disease
- congenital cause
uncommon
- autoimmune liver disease
- haemochromatosis (iron salts deposited in tissues)
- Wilsons disease (excess copper build up in the body)

Question 12

What does the urine and stools look like in someone with hepatocellular jaundice and why

Answer 12

Bilirubin is formed at a normal rate but the comprised liver cannot excrete it

-unconjugated bilirubin increased so deffo jaundiced but weather the urine is dark or the stools are pale is variable

Question 13

presenting symptoms/observations are variable in hepatocellular jaundice so what clinical test can help to differentiate this

Answer 13

liver biochemistry will show and elevation in transaminases (ALT)

Question 14

what does ALT/AST do

Answer 14

breaks down proteins and amino acids within the live

Question 15

what are the causes of haemolytic jaundice

Answer 15

RBC abnormalities eg sickle cell disease
due to incomplete blood transfusions
drug reaction
hypersplenism

Question 16

what do the urine and stools look like in haemolytic jaundice and why

Answer 16

urine is yellow and stools are normal because;

• the enzyme in the hepatocyte that conjugates bilirubin becomes saturated so there is a back-flow of UB in the blood

Question 17

Why is it so common for neonatal to be jaundices

Answer 17

the enzyme glucose transaminase (converting enzyme in the hepatocyte) doesn’t become properly functional until 40 weeks gestation
also bilirubin can cross the BBB so toxic to neural tissue (bilirubin encephalopathy)

Question 18

unconjugated hyperbilirubinaemia is toxic and what is the term used to denote the clinical features of acute or chronic bilirubin encephalopathy

Answer 18

kernicterus (yellowing of the brain tissue)

Question 19

Conjugated hyperbilirubinaemia is non-toxic and always pathological. What does it indicate

Answer 19

theres an obstruction to the excretion of bile (biliary atresia is the rare form where the biliary tree doesn’t form)

Question 20

What things can be used to treat unconjugated hyperbilirubinaemia

Answer 20

fluid and caloric intake will prevent worsening of jaundice
phototherapy (to break down bilirubin)
exchange transfusion in extreme cases

Question 21

When investigating jaundice in an adult what things do you need to explore in the HOPC

Answer 21

if they have jaundice with or without pain
the duration of the jaundice
is there any itching
what is the colour of the urine and stools

Question 22

when investigating jaundice in an adult what things do you need to explore in the social history

Answer 22

drug and alcohol use
cigarette use
foreign travel
sexual history (there is a link between hep B and obstructive jaundice

Question 23

When investigating jaundice in an adult what things would you be looking for on general examination

Answer 23

o Sclera and skin
o Scratches from pruritus
o Evidence of weight loss (thenar wasting)- first web space of fingers
o Troisier’s node aka vircoffs sign (left supraclavicular node enlargement)- note that the proximal intestine drains through the thoracic duct)

Question 24

When investigating jaundice in an adult what tests would you want to perform and what are you looking for

Answer 24

trans-abdo ultrasound: to look for evidence of dilated bile ducts

CT scan to look for dilated pancreatic duct perhaps

Endoscopic retrograde cholangiopancreatography (ERCP) which is where they put a camera to the ampulla in the duodenum - to look for gallstones