Patients_Liver & Biliary Flashcards
7 α-Hydroxylase - function?
Breaks down cholesterol during synthesis of Bile
Where is fat absorbed?
Ileum
3 enzymes necessary for fat absorption/
- Lipase (pancreas)
- Bile salts (gall bladder)
- Enterocytes
Bile salt synthesis includes conjugation w/ what 2 amino acids?
Taurine & Glycine
What is the rate-limiting step of bilirubin conjugation?
The transfer of conjugated bilirubin from the hepatocyte into the cannaliculi
Is Bilirubinuria due to conjugated or unconjugated bilirubin in the urine?
Conjugated (always)
(b/c unconjugated bilirubin is attached to albumin & this is too large to be excreted by kidneys)
**this is always pathologic
Is it ever normal for bilirubin to be in the urine?
No, this is always pathologic & due to massive hepatic injury (conjugated bilirubin released into blood upon hepatic injury)
(urobilinogen should be in urine, not bilirubin)
What is the molecular marker for Hepatocellular Carcinoma (HCC)?
α-fetoprotein (AFP)
Which labs are the markers of true “liver function?”
- Albumin
- Ammonia (converted → urea; this is more a test of liver failure)
- Prothrombin time
- Bilirubin (conjugation - both types)
Which labs are the markers of “structural integrity” of the liver?
- AST (more specific for alcoholic injury b/c produced in mitochondria as well as cytosol)
- ALT (more specific to liver, b/c AST will also increase in muscle damage, hemolysis)
Since Alkaline Phosphatase is synthesized in the liver & bones, what test distinguishes the source of an elevated Alk Phos?
γ-Glutamyl Transferase (GGT) indicates liver
Upon hemolysis, what is the carrying protein that binds to hemoglobin?
Haptoglobin
so levels are low in patients w/ hemolysis
What is Gilbert Syndrome?
Transient reduction in UDP-glucuronyl transferase activity
What is the black substance that builds up in the liver in Dubin Johnson Syndrome?
Polymers of epinephrine metabolites
Does an elevated Alkaline Phosphatase suggest Hepatocellular damage or Cholestasis?
Cholestasis
post-hepatic injury
A patient presents to the ER with right upper quadrant colicky pain and fever. They are most concerned that the patient has acute cholecystitis. Which of the following tests is most helpful in establishing acute cholecystitis as the cause of this patient’s complaints?
- Opacities in the right subcostal area on AXR
- Increased serum AST and ALT
- Failed gallbladder visualization on radionuclide biliary scan
- Highly reflective structures inside the gallbladder on U/S
- Distended duodenum on upper GI series
- Failed gallbladder visualization on radionuclide biliary scan
What Paraneoplastic properties does Hepatocellular Carcinoma (HCC) sometimes possess?
- Erythropoietin (↑HCT)
- PTH-rP (hypercalcemia)
- Hypoglycemia
Primary Biliary Cirrhosis – Cause?
Autoimmune destruction of intrahepatic bile ducts
What other diseases is Primary Biliary Cirrhosis related to?
Sjogren’s Syndrome
Primary Biliary Obstruction – what effect may this have on eyesight?
Worse night vision due to ↓vitamin A
REMEMBER: Biliary obstruction causes ↓ fat-soluble vitamin uptake
Which of the following mechanisms contribute most greatly to hepatocellular injury and centrilobular necrosis seen in acetaminophen toxicity?
- Glutathione Depletion
- Excessive Glucuronide Conjugation
- Excessive Sulfation
- Alcohol Dehydrogenase Depletion
- Glutathione Depletion
(Glutathione normally stabilizes NAPQI, which is formed by hydroxylation of Glucuronic acid & Sulfate. An overload in NAPQI formation can damage hepatocytes)
Acetaminophen toxicity primarily affects which Zone of the liver lobules?
Zone 3
Centrilobular Necrosis
