Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Updated: Feb 8 2022

Bilirubin Production and Excretion

  • Overview
    • Overview
      • bilrubin is a yellow-colored byproduct of hemoglobin (heme) metabolism
      • elevated levels of bilirubin causes jaundice, characterized by yellow skin and sclerae
      • in the newborn, short-lived RBCs results in increased production of unconjugated bilirubin as heme breakdown products, decreased conjugation due to immature UDP-glucuronosyltransferase, and increased enterohepatic circulation due to decreased gastrointestinal activity
  • Pathway
    • Steps from bilirubin production to excretion (see above)
      • (1) reticuloendothelial system (RES)
        • macrophages phagocytose sensescent erythrocytes
          • hemoglobin metabolism yields bilirubin
            • pathway: heme → biliverdin (green-colored) → bilirubin (yellow-colored)
      • (2) bloodstream
        • albumin binds bilirubin and complex is carried to liver
          • bilirubin-albumin complex = indirect bilirubin (water insoluble)
      • (3) liver
        • hepatocytes take up bilirubin
        • hepatic microsomes conjugate bilirubin with glucoronic acid
          • conjugation via UDP glucuronyl transferase
            • enzyme is synthesized slowly after birth, sometimes causing newborn jaundice
        • conjugated bilirubin = direct bilirubin aka water soluble
        • a portion of conjugated bilirubin is excreted in urine
        • remainder is secreted into bile and then into small intestine
      • (4) gastointestinal tract
        • in terminal ileum and colon, bilirubin is deconjugated by bacterial enzymes and metabolized to urobilinogen
          • 18% of urobilinogen is absorbed via enterohepatic circulation and delivered back to liver
          • 80% of urobilinogen is converted to stercobilin and excreted in feces
            • stercobilin gives characteristic color of feces
          • 2% of urobilinogen is converted to urobilin and excreted in urine
            • urobilin gives characteristic color of urine
1 of 0
Private Note

Attach Treatment Poll
Treatment poll is required to gain more useful feedback from members.
Please enter Question Text
Please enter at least 2 unique options
Please enter at least 2 unique options
Please enter at least 2 unique options