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
What 2 vitamins are stored in the liver?
A and B12
What LFTs actually access injury and inflammation?
Which is more specific for liver injury?
AST- mitochondria
ALT- cytosol
ALT is more specific because AST is released with cardiac, hemolysis, other tissue
alk phosphatase
GGT
Where are alk phos and GGT expressed?
When are they released?
They are in the biliary canalicular surface and are released when bile ducts are blocked
What are the pathological signs of apoptosis and necrosis of hepatocytes?
Apoptosis- Councilman bodies
Necrosis- balloon degeneration
When the aminotransferase level is above 500, what are the potential causes?
- Viruses
- Ischemia
- Drugs and Toxins
- Autoimmune (Host T lymphocytes)
- Obstructive
In apoptosis, _________ are preferentially released. In necrosis ____________ are released.
- aminotransferases
2. all enzymes
Where is ischemic injury first noted?
Centrilobular because it is last to receive blood supply
A patient has just traveled to Guatemala and has come in for a check up. Blood work shows AST>500. What is the likely cause?
Virus
A patient has just started a new drug and has AST>500. What is the likely cause?
Drug
A patient has been using cocaine. Now they have AST >500. What is the likely cause?
Ischemia
It is summer and a hyperthermic homeless man comes in. His AST>500. What is the likely cause?
Ischemia
A person comes in with dyspnea and shortness of breath. They have heart failure. AST >500. What is the likely cause?
Ischemia
A person presents with RUQ pain and an AST >500. What is the likely cause?
obstruction
In what 3 situations would you see LD or LDH elevation?
- necrosis from ischemia
- choledolithiasis
- acetaminophen toxicity
what is the relationship between jaundice and cholestasis?
They can each occur separately but there is a lot of overlap.
Jaundice- icterus/elevated bilibubin
Cholestasis = obstruction in the biliary system/elevated alk phos
Ex. of J without C = hemolysis, genetic conjugation disorders
Ex. of C without J = biliary obstruction that is incomplete so enough bile is able to keep serum bilirubin below 2-3mg/dL
A patient presents with jaundice,pruritis, steattorrhea. They have trouble driving at night and are bleeding very easily. What is the most likely problem?
What will be increased in the serum?
Cholestasis
Elevated:
- bile acids
- abnormal lipoprotein
- lipoprotein X
- bilirubin (CB and UCB) if complete obstruction, infiltrate, or severe liver disease
What are the 3 major symptoms of cholestasis?
- pruritus
- steatorrhea from lack of bile salt
- fat soluble vitamin deficiency from lack of bile salts
A patient presents with bleeding diathesis. What vitamin are they lacking? What is the likely problem?
Lacking vitamin K due to cholestasis
In cholestasis there is a lack of bile salts which cause deficiency of fat soluble vitamins. What are the 4 main fat soluble vitamins? What would be the major presenting symptom for each?
A- night blindness
D- osteomalacia
E- neuro deficit
K- bleeding
What causes intracellular cholestasis?
Disorders that interefere with the secretion into the bile canaliculus specifically:
hormones
drugs
What are causes of intrahepatic cholestasis?
Anything that obstructs or destroys bile ducts in the liver. For example:
- schistosoma
- sarcoid granulomas
- portal fibrosis
- PBC
What are examples of things that can cause extrahepatic cholestasis?
- benign strictures
- tumors of bile duct (cholangiocarcinoma)
- pancreatic tumors
What is the most cost-efficient/first imaging study used when stomes are suspected?
Ultrasound
What is cholangiography? When is it used?
PTC: It is X-ray of the liver and bile duct after the injection of contrast to see if there is blockage in the bile duct
ERCP- injection of contrast into the common bile duct to see if there is obstruction in the pancreas or biliary tree
It is used if you need to delineate the precise nature of an obstruction
When extrahepatic causes of cholestasis have been ruled out, what is the next lab test you should do?
Liver biopsy because there may be an intrahepatic cause like:
- PBC
- sarcoid granuloma
- portal fibrosis
- schistosoma
What is the disorder if there is positive AMA?
PBC
What is the disorder if there is pANCA and cholestasis?
primary sclerosing cholangitis
