Inherited Disorders of Bilirubin Metabolism

Question 1

Inherited Disorders of Bilirubin Metabolism

Answer 1

Gilbert’s Syndrome (Bilirubin Transport Deficit)
Crigler-Najjar Syndrome
Lucey-Driscoll Syndrome
Dubin-Johnson Syndrome (Bilirubin Excretion Deficit)
Rotor Syndrome

Question 2

Bilirubin Transport Deficit

Answer 2

Gilbert’s Syndrome

Question 3

Characterized by impaired cellular uptake of bilirubin due to genetic mutation on UGT1A1 gene (Chromosome #2)

Answer 3

Gilbert’s Syndrome

Question 4

T/F. Bilirubin can be transported to hepatocytes

Answer 4

False, Bilirubin cannot be transported to hepatocytes

Question 5

Affected individuals may have no symptoms but may have mild icterus and predisposed acetaminophen toxicity

Answer 5

Gilbert’s Syndrome

Question 6

Laboratory Findings: Gilbert’s Syndrome
o Indirect Bilirubin:

Answer 6

o Indirect Bilirubin: 1.5-3.0 mg/dL (increase)

Question 7

Conjugation deficit (UDPGT problem)

Answer 7

Crigler-Najjar Syndrome

Question 8

Chronic Non-hemolytic unconjugated hyperbilirubinemia

Answer 8

Crigler-Najjar Syndrome

Question 9

Crigler-Najjar Syndrome Laboratory result:

Answer 9

Elevated Indirect bilirubin

Question 10

Crigler-Najjar Syndrome Treatment:

Answer 10

Phototherapy

Question 11

Complete deficiency of uridine diphosphate glucuronosyltransferases (UDPGT)

Answer 11

Crigler-Najjar Syndrome Type 1

Question 12

Laboratory findings: Crigler-Najjar Syndrome Type 1
o Indirect bilirubin:
o Direct bilirubin:

Answer 12

o Indirect bilirubin: >25 mg/dL
o Direct bilirubin: None

Question 13

Crigler-Najjar Syndrome Type 1 Symptoms:

Answer 13

Kernicterus, colorless bile

Question 14

Partial deficiency of UDPGT

Answer 14

Crigler-Najjar Syndrome Type 2

Question 15

Laboratory results: Crigler-Najjar Syndrome Type 2
o Indirect bilirubin:

Answer 15

o Indirect bilirubin: 5-20 mg/dL

Question 16

Familial form of unconjugated hyperbilirubinemia caused by circulating inhibitor of bilirubin conjugation

Answer 16

Lucey-Driscoll Syndrome

Question 17

Laboratory findings: Lucey-Driscoll Syndrome
o Indirect bilirubin:

Answer 17

o Indirect bilirubin: Increased (2-3 weeks of life)

Question 18

Bilirubin Excretion Deficit

Answer 18

Dubin-Johnson Syndrome

Question 19

Conjugated hyperbilirubinemia

Answer 19

Dubin-Johnson Syndrome

Question 20

Defective excretion of direct bilirubin into the canaliculi caused by hepatocyte membrane defect

Answer 20

Dubin-Johnson Syndrome

Question 21

Characterized of an intense dark pigmentation of the liver due to accumulation of lipofuscin pigment → “Black liver”

Answer 21

Dubin-Johnson Syndrome

Question 22

• Similar with Dubin-Johnson syndrome without the black liver
• Unknown cause

Answer 22

Rotor Syndrome

Question 23

Laboratory findings: Rotor Syndrome
o Elevation in direct bilirubin (not excreted) and total bilirubin
o Delta bilirubin:

Answer 23

Increased