Bilirubin

Question 1

how do you diagnoses breastfeeding jaundice

Answer 1

stop breastfeeding, rapid decline in jaundice

Question 2

5 categories of Pathologic Jaundice

Answer 2

Increased load of bilirubin (heme catabolism)
disorders of hepatic uptake
disorders of conjugation
disorders of excretion
disorders of enterohepatic circulation

Question 3

Neonates have high content of unconjugated bilirubin in intestine because

Answer 3

1. Exaggerated hydrolysis of bilirbuin glucoronide
2. high concentrations of bilirubin in meconium
3. Lack of bacterial flora to reduce bilirubin to urobilogen
4. High mucosal B-glucorindase

Question 4

what is difference between Cirgler-Najarr 1 vs 2.

Answer 4

1 is Autosomal recessive, almost complete absence of UDP
no response to Phenobarb
needs liver transplant

type 2, autosomal recessive and dominant
UDP non existent
less severe than type 1
responds to phenobarb

Question 5

Where does bilirubin bind in brain?

Answer 5

Bilirubin binds primarily to the globus pallidus (part of basal ganglia) but also to the hippocampus, cerebellum, and subthalamic nuclear bodies, causing neurotoxicity through apoptosis and necrosis.

Question 6

this medicine acts by excretion of bilirubin by stimulating the gene for the UGT1A1 enzyme that induces the production of conjugated bilirubin

Answer 6

Phenobarbital

Question 7

UDP-glucuronosyltransferase acts how?

Answer 7

conjugates bilirubin with glucuronic acid making bilirubin water-soluble and easily excreted in bile

Question 8

unbound bilirubin is indirectly proportional to

Answer 8

albumin

Question 9

Enterohaptic circulation
intestinal bilirubin is reabsorbed in ___________ and returns to liver via_______-

Answer 9

intestinal mucosa
portal circulation
(25% of total bilirubin excreted into intestine is reabsorbed)

Question 10

what albumin level is neurotoxicity risk factor in hyperbiil?

Answer 10

less than 3.0

Question 11

What type of isomerization is responsible for bilirubin decrease in phototherapy?

Answer 11

Structural isomerzation
Bilirubin also undergoes an irreversible intramolecular cyclization on light exposure, rendering bilirubin more polar. This structural isomer is called lumirubin. Lumirubin is transported to the liver and excreted (unconjugated) in the bile and to a lesser degree in the urine. This process is the major contributor to the lowering of total serum bilirubin concentration due to phototherapy.

Configural isomerization
This reaction is immediate but reversible, and the concentration of the water-soluble 4Z,15E isomer can approach approximately 20% of the concentration of the 4Z,15Z isomer. These hydrophilic isomers reduce the exposure of the brain to the toxic, lipid-soluble configuration.