LFT Module (Quiz 3) Flashcards
which LFTS are indicators of hepatocellular injury
another name for them
- AST (SGOT)
- ALT (SGPT)
which LFTs are indicators of cholestasis or obstruction (bile duct injury or obstruction)
- alkaline phosphatase
- GGT
- bilirubin
which LFTs are indicators of true liver function
- bilirubin
- albumin
- PT/INR
when we talk about hepatocellular injury, we mean that what has been damaged
- actual hepatocytes
what do we mean when cholestatic or biliary injury has occurred
- cells that compose the wall of bile ducts have been damaged
- impaired bile formation or impaired bile flow
AST and ALT play a role in what process
- gluconeogenesis
AST produces
ALT produces
- oxaloacetate
- pyruvate
between AST and ALT, which is more specific for liver disease
- ALT
- AST is located in many places
highest levels of amino transferases are found with what
- ischemic injury
- drug-induced liver injury
what is cholestasis
- impairment of biliary flow
the elevation in alkaline phosphatase in cholestatic diseases is thought to be secondary to _______________ due to enhanced translation of the mRNA of alkaline phosphatase
- increased synthesis
between GGT and alkaline phosphatase, which is more sensitive and has the best negative predictive value
- GGT
GGT may become elevated due to enzyme induction from ________-
- alcohol
what will albumin levels be during periods of liver injury or severe inflammation
- decreased
what happens to the PT/INR during liver damage
- prolonged
bilirubin is a toxic metabolite generated by what process
- breakdown of hemoglobin from RBC
bilirubin circulates through the blood how
- in an insoluble, unconjugated form
- complexed with albumin
once bilirubin is taken into hepatocytes, it gets conjugated with ____________ by which enzyme
purpose
- glucouronic acid
- UGT
- make bilirubin soluble
what happens with conjugated bilirubin
via which protein
- secreted from hepatocytes into bile
- cMOAT/MRP-2
bilirubin is broken down by gut bacteria into
fate of these products
- sterocobilinogen - excreted in stool
- urobilinogen - reabsorbed by enterohepatic circulation
how do we synthesize bilirubin
- heme -> biliverdin -> bilirubin
how do we produce heme -> biliverdin
- heme oxygenase opens heme ring
how do we produce biliverdin -> bilirubin
- bilirubin reductase reduces central methylene bridge of biliverdin
classify the bilirubin formed in the reticuloendothelial cells
- lipid soluble
- insoluble in water
- unconjugated bilirubin
does the liver take up bilirubin and albumin?
- no
the ______ bilirubin is that which reacts within 1 minute, whereas the _______ bilirubin is the amount which reacts 30 minutes after the addition of alcohol
- direct bilirubin
- total bilirubin
how to calculate indirect fraction of bilirubin
- total bilirubin minus direct bilirubin
hemolytic disorders and ineffective erythropoiesis lead to (conjugated or unconjugated) hyperbilirubenemia
- unconjugated
what is a serious condition causes hyperbilirubinemia in infants called?
- kernicterus
hepatocellular dysfunction and intrahepatic cholestais cause (conjugated or unconjugated) hyperbilirubenemia
how
- conjugated
- blocks transit of bilirubin from hepatocytes
are LFTs normal with indirect hyperbilirubinemia?
what about with direct
- yes
- no; elevated
pre-hepatic jaundice leads to elevation of direct or indirect bilirubin
when does it occur
- indirect
- prior to bilirubin uptake by the liver
intra-hepatic jaundice leads to elevation of direct or indirect bilirubin
when does it occur?
- direct and indirect
- when hepatocytes are damaged
- can’t conjugate bilirubin or leakage of conjugated bilirubin
post-hepatic jaundice leads to elevation of direct or indirect bilirubin
when does it occur?
- direct
- impaired excretion of bilirubin in the biliary tree
which disorders of bilirubin metabolism are disorders of conjugation
caused by what
- gilbert syndrome
- crigler najjar syndrome
- alterations in gene that produces UGT
which disorders of bilirubin metabolism are disorders of excretion into bile
- Dubin johnson syndrome
which disorders of bilirubin metabolism are disorders of reuptake
- rotor syndrome
what is the most common hereditary hyperbilirubinemia syndrome that is associated with at least a 50% loss of UGT activity and results in a mild, intermittent, isolated unconjugated hyperbilirubinemia
- gilbert syndrome
which type of Crigler Najjar syndrome is characterized by absent or nearly absent UGT1A1 enzyme activity
which type is characterized by reduced by not absent UGT1A1 activity
- Type I
- Type II
which type of Crigler Najjar syndrome is caused by multiple deleterious mutations
which type of Crigler Najjar syndrome is caused by a point mutation in a single amino acid residue, which leads to reduced, and not absent enzyme activity
- Type I
- Type II
which type of Crigler Najjar syndrome is associated with bilirubin encephalopathy and death without administration of aggressive phototherapy and exchange transfusions
treatment
- Type I
- liver transplantation
which disorder of bilirubin metabolism results from absent or deficient expression of the gene ABCC2/MRP2 that leads to absent transcription of or failure of translocation of the bilirubin transporter to the canalicular membrane.
how do you diagnose it
what are their levels
will the liver be pigmented
- Dubin-Johnson syndrome
- measure coproporphyrin I levels
- around 80%
- yes, black
which disorder of bilirubin metabolism is characterized by hepatic uptake and storage of bilirubin that results in the absence of OATP1B1 and OATP1B3 transporters
how do you diagnose it
what are their levels
will the liver be pigmented
- rotor syndrome
- measure coproporphyrin I levels
- around 65%
- no
which is elevated in hepatocellular injury (AST/ALT or alkaline phosphatase)
- AST/ALT elevated greater than alkaline phosphatase
what is the AST/ALT ratio for alcoholic hepatitis
2-3:1
which is elevated in cholestatic injury (AST/ALT or alkaline phosphatase)
what accompanies this
- alkaline phosphatase is elevated more than the transaminases
- direct hyperbilirubinemia
intrahepatic cholestasis refers to
- impaired excretion of conjugated bilirubin
extrahepatic cholestasis refers to
- bile duct obstruction
which is elevated in infiltrative diseases like sarcoidosis, lymphoma, tuberculosis (AST/ALT or alkaline phosphatase)
- alkaline phosphatase
one of the more common places for bile duct stones to get stuck is where
- common bile duct
what is the most important aspect of liver imaging
- evaluate for biliary ductal obstruction
two types of liver biopsy
where are they performed
- percutaneous - bedside
- transjugular - VIR suite
