CM- Jaundice and Cholestasis Flashcards
What are the major components of bile?
Bile acids, bile salts, and biliary acids.
Bilirubin is only a MINOR component of bile
What are the 4 main EXOCRINE functions of the liver?
- synthesize and secrete bile acids to digest fat/fat soluble vitamins
- Metabolize and excrete bilirubin
- transform and excrete drugs and toxins
- metabolize and excrete lipids
What happens to bilirubin when it enters the hepatocyte?
It is conjugated by glucuronidation. The conjugated bilirubin is pushed out the bile canaliculi and a little bit goes back into the blood
What is the polarity and lipid solubility of bilirubin before it is conjugated in the hepatocyte?
it is non-polar and lipid soluble.
What is a situation where DB and TB are elevated and the other liver enzymes are not elevated?
Dubin-Johnson an Roder syndrome
Unconjugated hyperbilirubinemia can occur from increased __________ or decreased ____________.
Increased hemolysis or decreased output into bile (conjugation defect)
CB increased along with unconjugated in which situations?
- transporter defect from the hepatocyte to the bile canaliculi
- back flux of bilirubin from hepatic AND biliary disease
What level of bilirubin in circulation is associated with jaundice?
2-3mg/dL
What are the 3 situations that cause isolated increase in bilirubin?
- hemolysis (prehepatic)
Hepatic:
- defective conjugation (common, genetic)
- impaired excretion into bile (rare, genetic)
What are causes of hyperbilirubinemia when it is accompanied by other lab abnormalities?
- acute/chronic hepatitis
- cholestatic and infiltrative liver disease
- biliary tract obstruction
What are the UCB and CB levels in hemolysis?
UCB- increased
CB - normal
What are the UCB and CB levels in Gilbert’s syndrome?
What causes this disorder?
What conditions exacerbate ?
What is the similar yet more severe disorder?
UCB- high
CB- low/normal - due to conjugation defect in hepatocyte
AD promotor defect in glucuronyl transferase
It is exacerbated by stress
Crigler-Najjar is the more severe disorder
What are the levels of CB and UCB in Dubin-Johnson?
CB is increased with TB because conjugation is fine but the bilirubin is not excreted into the bile canaliculi
Why does sepsis cause hyperbilirubinemia?
cytokines decrease transporter genes on the apical side of the hepatocyte so CB cannot enter the bile canaliculi
It also increases transporters on basolateral side so CB can enter the blood
What happens to the haptoglobin level with intravascular hemolysis?
It is decreased because it binds to bilirubin
What two tests are helpful to determine if hyperbilirubinemia is pure UCB or mixed?
- Bilirubin fractionation - measure TB and CB and calculate UCB
- Test for bilirubin in urine. It will be positive if CB is elevated.
In what two situations are hyperbilirubinemia NOT benign?
- Infants after 2 wks b/c may be a sign of biliary atresia
2. rare patients with conjugation defects
What are the endocrine functions of the liver? What LFTs measure this?
Synthesize plasma proteins except immunoglobulins
Synthesize clotting factors except 8
LFTs are:
- total protein
- PT
- Albumin