What does Hgb break down into?
unconjugated (indirect) bilirubin
Heme breaks down into:
biliverdin --> bilirubin
What type of bilirubin is toxic and lipid soluble?
unconjugated (indirect) bilirubin
What does unconjugated (indirect) bilirubin bind to?
Albumbin
Where does UCB bound to albumin travel?
Liver
Where is bilirubin conjugated?
Liver
What is bilirubin conjugated with?
glucuronic acid via the enzyme UDP glucuronyl transferase
What type of bilirubin is water soluble?
conjugated (direct) bilirubin
What type of bilirubin is excreted in urine and secreted into bile?
conjugated (direct) bilirubin
What is conjugated (direct) bilirubin converted to in the intestines?
Urobilinogen
Urobilinogen eventually becomes:
Feces
What is the result of hyperbilirubinemia?
Jaundice
Why does jaundice occur in the sclera first?
bilirubin has affinity for elastin
Jaundice typically occurs with a serum bili:
, > 4-5 mg/dL
What are the four major causes of jaundice?
- excessive RBC destruction
- impaired uptake of bilirubin by hepatocytes
- decreased conjugation of bilirubin
- bile flow obstruction
What is the mechanism of prehepatic jaundice?
excessive RBC destruction (increased hemolysis)
What is the result of prehepatic jaundice?
increased unconjugated (indirect) bilirubin
What is an example of prehepatic jaundice?
hemolytic anemia
What is the mechanism of intrahepatic jaundice?
impaired bilirubin uptake or decreased conjugation
What is the result of intrahepatic jaundice?
increased unconjugated and conjugated bilirubin
What are examples of intrahepatic jaundice?
- hepatitis
- cirrhosis
- Dubin-Johnson syndrome
What is the mechanism of posthepatic jaundice?
bile flow obstruction
What is the result of posthepatic jaundice?
increased conjugated (direct) bilirubin
What are examples of posthepatic jaundice?
- gallstone
- malignancy
- inflammation
↓ bilirubin elimination via biliary tract
posthepatic jaundice
What is inflammation of the liver?
Hepatitis
What is viral hepatitis?