HEME BREAKDOWN
Enzyme converting heme → biliverdin?
Heme oxygenase.
What carries unconjugated bilirubin in blood?
Albumin.
Enzyme responsible for conjugation?
UDP-glucuronyl transferase (UGT1A1).
Transporter that secretes CB into bile?
MRP2 (MOAT).
Type of bilirubin elevated in hemolysis?
Unconjugated.
Biliverdin → bilirubin is catalyzed by?
Biliverdin reductase.
Hepatic protein preventing bilirubin efflux?
Ligandin.
Where does conjugation occur?
Smooth endoplasmic reticulum.
Intestinal enzyme hydrolyzing bilirubin diglucuronide?
β-glucuronidase.
Type elevated in obstruction?
Conjugated.
Which gas is released during heme degradation?
Carbon monoxide (CO).
Why is UCB absent in urine?
It is albumin-bound & insoluble.
mmediate product of single glucuronic acid addition?
Bilirubin monoglucuronide.
Pigment giving stool its brown colour?
Stercobilin.
Which jaundice has ↑ urine urobilinogen?
Hemolytic jaundice.
What happens to iron released during heme breakdown?
Recycled via transferrin.
Location of bilirubin uptake in hepatocytes?
Sinusoidal membrane transport.
Final conjugated form excreted in bile?
Bilirubin diglucuronide.
Why is urine dark in obstructive jaundice?
Conjugated bilirubin spills into urine.
Jaundice with biphasic Vandenberg reaction?
.
Hepatic jaundice
Why does massive hemolysis cause ↑ unconjugated bilirubin?
Liver conjugation capacity is exceeded.
What increases free UCB and risk of kernicterus in neonates?
Drugs that displace UCB from albumin (e.g., sulfonamides).
Why do neonates develop physiological jaundice?
Immature UGT enzyme activity.
Why are stools pale in obstruction?
Absence of bilirubin → no stercobilin formation.
A patient has pale stools + itching. Type of jaundice?
Obstructive jaundice.