Bile Secretion and Gall Stone Disease Flashcards
What kinds of bile flow are there?
bile acid dependent or bile acid independent.
dependent: hepatocytes secrete bile into ducts and water follows the osmotic gradient.
Independent: ducts secrete bicarb and mucin fluid into the ducts in a secretin/CCK-mediated pathway
Roles of the gallbladder
- store bile when the body is fasting
- release bile in response to fat consumption
- concentrate stored bile
Main types of gallstones
cholesterol stones (enveloped shaped) and bilirubin stones
Bilirubin metab
Heme from RBCs and muscles converted to biliverdin, CO, and Fe3+ by heme oxygenase. biliverdin is converted to bilirubin and is transported in the serum associated with albumin (unconjugated bilirubin)
Liver takes up bilirubin and binds it to Y protein.
Bilrubin + Y protein go to the endoplasmic reticulum.
UGT1A1 addes side chains to bilirubin –> water soluble and ready for excretion.
Conjugated bilirubin is excreted in the bile. Bacteria in the bowel convert conjugated bilirubin to stercobilinogen/urobilinogen. Some excteted in the urine. Stercobilinogen is oxidized to stercobilin
Gilbert’s syndrome
UGT1A1 doesn’t work- unconjugated bilirubinemia. dangerous in neonates. can’t give these pts ironitecan
What are bile acids
made by hepatocytes from cholesterol and then conjugated with amino acids. amphipathic detergents. important for helping fat digestion via emulsification and incr. surface area; incr. absorption of fat soluble vitamins; decr. bacterial overgrowth in the small intestine
types of bile acids
cholic and chenodeoxycholic acid. bacteria convert bile acids to secondary (bad) bile acids deoxycholic and ithocholic acids– toxic and lithogenic.
what is the enterohepatic ciculation of bile acids
bile acids made by liver, stored in gall bladder, released in gut, reabsorbed and returned to liver via protal vein.
risks and types of gallstones disease
risks: female, overweight, pregnant, OCPs, Native American, sudden weight loss, hemolytic anemias
types: yellow cholesterol stones with Ca.
black calcium bilirubinate from chronic hemolysis
brown stones from bacterail action on bile
when do cholesterol stones occur in the gallbladder?
- Oversaturation with cholesterol or not enough bile acids: obesity, high fat diet, acute weight loss, liver disease
- Seeding of a stone (cholesterol monohydrate crystal nucleation)- from bacterial or mucin seed
- gallbladder stasis: fasting, TPN
Clinical presentation of gallstones
usually asymptomatic- no tx needed
others: RUQ epigastric pain post-prandially, often associated with nausea and vomiting. lasts 1-6 hrs.
Complications of gallstones
acute cholecystitis, bile duct obstruction and jaundice, infection, gallstone pancreatitis
Dx and Tx of gallstone disease
Dx: ultrasound
Tx: none if asymptomatic. If symptomatic, do elective cholecystectomy. Or, give URSODIOL if pt not gandidate for surgery. works better with less calcium, small stones, if gallbladder fills and empties well.
What is acute cholecystitis?
acute infection/inflammation of the gallbladder, usually due to blockage of the cystic duct by a gallstone. If bacteria grow, you may see abscesses, fever, chills, peritonitis.
This is a surgical emergency and requires immediate cholecystectomy
Dx of acute cholecystitis
biliary cholic and RUQ pain
exam: RUQ pain, rebound tenderness.
U/S shows gallstones and sludge, thickened distended bladder.
may do a TC99 taged HIDA with nonvisualization of gallbladder with contrast going from liver into the bowel.
Tx: cholecystectomy. give abx, IV fluids, pain meds
What is choledocholithiasis
Stones in the bile duct. may be asymptomatic, or pts may present with serous complications like pancreatitis or cholangitis
Clinical signs of choledocholithiasis
Pain. Charcot’s triad: pain, fever, jaundice is suggestive of ascending cholangitis
Dx of choledocholithiasis
labs and imaging w/ U/S, CT, MRCP. ERCP is more invasive, but if you make the diagnosis, you can also treat
Tx of choledocolithiasis
URGENT
IV fluids, abx, biliary decompression/drainage.
ERCP (best) or percutaneous transhepatic cholangiography
What is primary sclerosing cholangitis
chronic inflammatory disease that affects the large and medium sized bile ducts. may lead to fibrosis, cirrhosis and liver failure
Epi of primary sclerosing cholangitis
more in men than women
associated with IBD, esp. ulcerative colitis. one dx may precede the other.
Pathogenesis and markers for primary sclerosing cholangitis
auto-immune with pANCA and ANA.
poor progonsis: 10-12 yrs w/o transplant
Presentation of primary sclerosing cholangiits
usually in pts aged 20-40
jaundice, pruritis, fatigue and/or mixed cholestatic hepatic enzyme elevation. may presents with ascending cholangitis or sepsis. occasionally presents with cholangiocarcinoma.
Dx of primary sclerosing cholangitis
imaging of the bile ducts via MRCP or ERCP.
Beading, dilation, and strictures of the main bile duct or branches
may need liver biopsy
classically, see periductal onion skinning.
Management of primary sclerosing cholangiitis
nothing, really. treat complications. look for IBD. manage cirrhosis. Maybe liver transplant, though disease frequently recurs.
many develop cholangiocarcinoma
do colonoscopy to look for asymptomatic IBD; if present, do additional screening for colon CA
