A
Jaundice is not clinically visible until bilirubin exceeds this plasma level
2.0 mg/dL
What protein carries unconjugated bilirubin in blood for transport?
Albumin
Which enzyme in the liver conjugates bilirubin?
UDP-glucoronyl transferase
Similar to Dubin-Johnson but without pigmentation
Rotor Syndrome
Which type of bilirubin is present in urine?
Conjugated/Direct/B2 bilirubin
In patients with polycythemia, which type of bilirubin predominates?
Unconjugated/Indirect/ B1 Bilirubin
Which enzyme converts heme to biliverdin?
Heme oxygenase
Which form of bilirubin is neurotoxic and can cause kernicterus?
Unconjugated/Indirect/B1 bilirubin
Product produced from intestinal bacterial action on B2
Urobilinogen
Why does type I of Crigler-Najjar syndrome causes severe neonatal jaundice with kernicterus?
Complete absence of UDPGT
Cofactor needed by ALA synthase for heme synthesis
Vitamin B6 (Pyridoxal phosphate)
Type of bilirubinemia associated with fat malabsorption
Conjugated hyperbilirubinemia
What is the cause of Lucey-Driscoll Syndrome?
Presence of UDPGT inhibitor that prevents bilirubin conjugation
Management for physiologic jaundice of the newborn to prevent kernicterus if the bilirubin level is already dangerously high
Exchange transfusion
Dubin-Johnson syndrome leads to impaired excretion of conjugated bilirubin because of?
Defective MRP2 (multidrug resistance protein 2) transporter
A 45-year-old patient presents with yellowing of the eyes. Labs and findings are as follows:
Serum bilirubin: elevated, mostly direct (conjugated)
Urine bilirubin: positive;
Urine urobilinogen: absent;
Symptoms: pruritus, abdominal pain after fatty meals;
Questions:What type (pre-,hepatic,post-) of jaundice does this patient have? What do you expect would be the color of the urine & stool?
Post-hepatic (obstructive) jaundice, because conjugated bilirubin is water-soluble and leaks into urine (positive urine bilirubin → dark urine) bile cannot reach the intestine (obstruction) → no stercobilin formation → pale/clay-colored stool