Biochemistry of Jaundice

Question 1

overview of jaundice

Answer 1

yellow coloring of eyes and skin
caused by build up of bilirubin in plasma which causes hyperbilirubinemia
is visible when bilirubin>3mg/dL
symptoms: nausea, vomiting, dark urine, fatigue

Question 2

bilirubin

Answer 2

yellow, water insoluable compound but is made water soluable to use in bile, urine
its a waste products of heme breakdown from RBCs
2 types: unconjugated, conjugated

Question 3

heme metabolised into bilirubin

Answer 3

pre-hepatic: formation, plasma transport
hepatic: liver uptake, conjugation
post-hepatic: biliary excretion

Question 4

formation of bilirubin

Answer 4

haemoglobin oxidised biliverdin (green) which is then reduced to unconjugated bilirubin (orange) which is insoluable in water

Question 5

plasma transport

Answer 5

bilirubin binds strong to albumin and is transported to liver via plasma
binding to albumin increases its solubility and stops it binding to other substances

Question 6

liver uptake

Answer 6

when bilirubin is released from albumin and is taken up by liver

Question 6

conjugation of bilirubin

Answer 6

in liver cells bilirubin is converted to bilirubin diglucuronide which is conjugated bilirubin which is water soluable and goes to bile to be excreted

Question 7

excretion of bilirubin

Answer 7

conjugated bilirubin is secreted in bile and goes to intestine
gut bacteria changes CB into urobilinogen (excreted as stools) which is further oxidised into urobilin (excreted in urine) and sterocobilin (reabsorbed into liver)

Question 8

types of jaundice

Answer 8

hemolysis- excess RBC breakdown for more bilirubin in blood
causes: sickle cell anemia, pyruvate kinase deficiency

hepatocellular- liver cells damaged so cont convert bilirubin so more in blood
causes- cirrhosis, hepatitis

obstructive- drainage is blocked so bilirubin stay in blood
causes- tumor or bile stones blocking bile duct, leads to GI pain or nausea

Question 9

important test to screen jaundice

Answer 9

blood samples
urea
liver function tests
amylase
viral hepatitis screen

Question 10

gall bladder disorders

Answer 10

cholelithiasis- gallstone formation in gallbladder
cholecystitis- stone in cystic duct causing inflammation
choledocolithiasis- stone in bile duct causing inflammation
cholangitis- stone in bile duct cause infections