BLD 402 BILIRUBIN EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++
Bilirubin formation
Spleen:
1. Separates heme from globin
2. Heme oxygenate converts it to biliverdin
3. biliverdin reductase converts it to unconjugated bilirubin
Blood flow:
1. Unconjugated bilirubin binds to albumin because it is insoluble in water
Liver:
1. Hepatic uptake: unconjugated bilirubin binds to transport protein to cross the hepatic
cell membrane and leaves albumin
2. In hepatocytes, unconjugated bilirubin binds to lignin because it is insoluble in water
3. conjugation: uridine diphosphate (UDP)-glucuronyl transferace adds one or two
glucuronyl group = conjugated bilirubin
4. Conjugated bilirubin is excreted to bile canaliculus and becomes component of bile
Bile duct- intestine:
1. Intestinal flora converts conjugated bilirubin to urobilinogens (colorless)
2. Enterohepatic circulation: some of urobilinogens are reabsorbed at ileum to portal
vein to either re-excreted to bile or excreted from kidney. Urobilinogens in urine=
, urobilins (color or urine)
3. Intestinal flora conver urobilinogens to urobilins to stercobilins (brow color of feces)
Direct Bilirubin
Only conjugated bilirubin reacts when reaction is run without an additive because
unconjugated bilirubin is binding to albumin, reagents cannot approach. Conjugated
bilirubin reacts directly without additive= direct bilirubin
total bilirubin
Unconjugated bilirubin comes off from albumin (when additive is added)
Both conjugated and unconjugated bilirubin react = total bilirubin
Indirect bilirubin
calculated from total bilirubin and direct bilirubin
Indirect bilirubin= total bilirubin-direct bilirubin
Indirectly measured= indirect bilirubin
Jaundice
hyperbilirubinemia causing yellow discoloration of skin and mucous membranes
Prehepatic Jaundice
overproduction of unconjugated bilirubin (hemolytic anemia)
Characteristics:
1. Indirect bilirubin increase
2. Urobilinogen increase in still, serum, and urine
3. No bilirubin in urine because it is unconjugated bilirubin (water insoluble)
Hepatic Jaundice
COMPLETE SOLUTIONS GRADED A++
Bilirubin formation
Spleen:
1. Separates heme from globin
2. Heme oxygenate converts it to biliverdin
3. biliverdin reductase converts it to unconjugated bilirubin
Blood flow:
1. Unconjugated bilirubin binds to albumin because it is insoluble in water
Liver:
1. Hepatic uptake: unconjugated bilirubin binds to transport protein to cross the hepatic
cell membrane and leaves albumin
2. In hepatocytes, unconjugated bilirubin binds to lignin because it is insoluble in water
3. conjugation: uridine diphosphate (UDP)-glucuronyl transferace adds one or two
glucuronyl group = conjugated bilirubin
4. Conjugated bilirubin is excreted to bile canaliculus and becomes component of bile
Bile duct- intestine:
1. Intestinal flora converts conjugated bilirubin to urobilinogens (colorless)
2. Enterohepatic circulation: some of urobilinogens are reabsorbed at ileum to portal
vein to either re-excreted to bile or excreted from kidney. Urobilinogens in urine=
, urobilins (color or urine)
3. Intestinal flora conver urobilinogens to urobilins to stercobilins (brow color of feces)
Direct Bilirubin
Only conjugated bilirubin reacts when reaction is run without an additive because
unconjugated bilirubin is binding to albumin, reagents cannot approach. Conjugated
bilirubin reacts directly without additive= direct bilirubin
total bilirubin
Unconjugated bilirubin comes off from albumin (when additive is added)
Both conjugated and unconjugated bilirubin react = total bilirubin
Indirect bilirubin
calculated from total bilirubin and direct bilirubin
Indirect bilirubin= total bilirubin-direct bilirubin
Indirectly measured= indirect bilirubin
Jaundice
hyperbilirubinemia causing yellow discoloration of skin and mucous membranes
Prehepatic Jaundice
overproduction of unconjugated bilirubin (hemolytic anemia)
Characteristics:
1. Indirect bilirubin increase
2. Urobilinogen increase in still, serum, and urine
3. No bilirubin in urine because it is unconjugated bilirubin (water insoluble)
Hepatic Jaundice
