Tombazzi - Gallbladder Flashcards
What are the components of bile (and their functions)?
- BILE ACIDS: solubilization of cholesterol and modulation of intestinal motility -> essential for fat absorption
- PHOSPHOLIPID: solubilization of cholesterol and protection of bile duct epithelium
- IgA and IgM: bacteriostasis
- MUCUS: prevention of bacterial adhesion
- GLUTATHIONE: induction of bile flow
- 500-600mL per day, and isoosmotic w/plasma
What 3 types of stones can form in the gallbladder?
- CHOLESTEROL: more frequent, yellow-white, Ca salts of unconjugated bilirubin, matrix of mucin glyoprotein, only occasionally seen by x-ray
- BLACK (pigmented): hemolysis, liver disease, age, TPN, pure calcium bilirubinate, calcium copper, mucin glycoprotein
- BROWN (pigmented): primary biliary, infection, prior surgery, duodenal diverticula, calcium salts and deconjugated bilirubin (high activity of beta-glucuronidase), cytoskeleton of bacteria, DEC biliary secretory IgA
Describe cholesterol metabolism. Hypersecretion? Risk factors for cholesterol stones?
- Total body pool of cholesterol: 1) syn from acyl-CoA, 2) dietary absorption, 3) cholesterol pool
1. Solubilized and secreted unmodified in bile, and converted to bile acids -> most important ways body gets rid of cholesterol - HYPERSECRETION:
1. Estrogen: INC receptors for lipoproteins, INC free cholesterol
2. Progesterone: DEC synthesis of cholesterol ester from free cholesterol - RISK FACTORS: female, older, obese, pregnant pts after delivery
- NOTE: remember all of these risk factors, and how they happen
What are the 3 most important contributing factors to the pathophys of cholesterol stone formation?
- Cholesterol supersaturation
- Accelerated nucleation
- Gallbladder hypomotility
- REMEMBER: balance b/t bile acid (good guy) and cholesterol (bad guy) is what is important
1. Cholesterol virtually insoluble in water, but bile acids, due to their unique amphiphatic properties, are able to solubilize cholesterol and phospholipid
What are 6 causes of cholesterol hypersecretion?
- OBESITY: hyperlipoproteinemia -> INC cholesterol synthesis (INC HMG CoA activity)
- PROGESTERONE: oral contraceptives INC free cholesterol -> INH AcoA CAT, DEC conversion of cholesterol to cholesterol ester stores
- ESTROGENS: INC cholesterol uptake via INC lipoprotein B and E receptors
- AGE: age-related DEC in 7-alpha-hydroxylase
- MARKED WEIGHT REDUCTION: mobilization of tissue cholesterol
- ILEAL DISEASE, bypass, or resection: impaired bile acid absorption or excessive losses
What is this?
- Abetalipoproteinemia: small bowel mucosa shows characteristic CLEAR ENTEROCYTES due to lipid accumulation
- Usually present as babies with failure to thrive
- Can’t get TG’s out of enterocytes, so they build up, and you get foamy, or frothy appearance from buildup of TG’s and lipoproteins in the enterocytes
- Note the difference b/t normal and diseased in the attached image
What is the cholesterol saturation index? How can cholesterol in bile be found?
- CSI: ratio of amt of cholesterol in a bile sample to its max cholesterol micellar-holding capacity -> max amt of cholesterol you can deal with considering the amt of bile acid you have available
- Bile that has a CSI >1 is supersaturated
- Cholesterol in bile can be found as the following:
1. Mixed micelle: bile acids (BA), cholesterol, bilirubin, PC (phosphatidyl choline)
2. Simple micelle: BA, cholesterol, bilirubin
3. Vesicles: 10x larger, no bile salts -> when these converge, you get stones
4. Multi-lamellar vesicles: unstable, and permit crystals formation
How can enterohepatic recirculation affect gallstone formation?
- Not enough bile acid can lead to imbalance b/t bile acids and cholesterol, so anything that can interfere with this circulation can get you into trouble
- Cycle occurs 6-10x daily
- Actively transported through the hepatocyte, stored in gallbladder, sent to small bowel, low absorption in jejunum, then active/passive absorption in ileum, and transport back to liver
What is accelerated nucleation?
- People who develop crystals much more quickly than others: some of these reasons we know, and others we do not
1. INC CSI = too much cholesterol for bile acid -
Crystal formation: aggregation process by which a crystal particle is formed from supersaturated bile
1. Crystals generation: vesicular fusion and aggregation
If 2 pts have cholesterol hyper-secretion, will they both have gallstones?
- MAYBE: don’t need to remember all of these in attached image, but know that there are other contributing factors -> 2 pts could have cholesterol hyper-secretion and 1 could have gallstones, and the other not
1. Hyper-secretion and hyper-saturation are 2 different things - Several factors identified that promote or INH the kinetics of cholesterol crystal formation:
1. Concentrating bile and secretion of mucin glycoprotein INC cholesterol crystal formation
2. Changes in bile composition, incl high cholesterol saturation and INC deoxycholate content enhance cholesterol crystallization
How can gallbladder emptying affect the formation of cholesterol stones? Provide an example.
- TPN: no food in duodenum, but gallbladder does not know, and NOT contract -> risk factor for stones
- Even w/o TPN, some ppl have more gallbladder activity than others
- People with gallstones tend to have hypo-active gallbladders, or delayed emptying
What are the gallbladder events in cholesterol gallstone formation? Possible risk factors? Tx?
- Possible RISK FACTORS:
1, Defective acidification of gallbladder bile
- > pH higher precipitation of calcium salts
- Gallbladder stasis can produce INC mucin secretion from gallbladder epithelium, and interfere with mechanical emptying
- Decreased response to CCK
- TX: remove gallbladder -> 95% of the time, you correct the problem - For most people, this is a gallbladder disease, with the exception of brown stones
What 4 factors are implicated in the pathophys of cholesterol gallstone formation?
- Hepatic cholesterol hypersecretion
- INC intestinal conversion to deoxycholate (2o bile acid)
- Mucin hypersecretion
- Gallbladder hypomotility
What are the clinical risk factors for black gallstone?
- Hemolysis, i.e., pts with sickle cell
1. A lot of bilirubin, which can precipitate with Ca salt, giving you small, hard stones (cholesterol stones are softer) - Advancing age
- Long-term TPN
- Cirrhosis
- High level of unconjugated bilirubin is main component -> beta-glucuronidase is the enzyme that un-conjugates bilirubin
What are the risk factors for brown pigmented stones?
-
Infection, primary biliary stones (formed in bile ducts, not gallbladder), prior surgery
1. Pts with intervention in the bile ducts; more frequently in older patients - DEC biliary secretory IgA
- High activity of B-glucuronidase
- Develop infection, inflammation, and bigger, softer, brown stones
Describe the anatomy of the extrahepatic biliary tree.
- Note that the common bile duct (CBD) passes through pancreas before duodenum, getting together with main pancreatic duct
What are the clinical manifestations of biliary colic?
- Abdominal pain
What are the clinical manifestations of acute cholecystitis?
- Abdominal pain
- FEVER
- Abdominal US: thickening of gallbladder wall and pericholecystic fluid (CT can also help)
1. Diagnostic
What are the clinical manifestations of choledocolithiasis with cholangitis?
- Abdominal pain
- Fever
- JAUNDICE
What are the clinical manifestations of biliary pancreatitis?
- Abdominal pain
- INC amylase
ER: 50-y/o obese F w/epigastric, RUQ abdominal pain (7/10) that lasts around 30 mins. Severe pain that goes up, stays there, then starts going down. No fever, but some tenderness in RUQ. No rebound or irritation.
You give her something for pain, and 30 mins later she is fine, and wants to eat.
What is going on? What should you do?
- BILIARY COLIC
- Send pt home, but tell her this can happen again
- Will need to schedule a surgery to take the gallbladder out
Pt. previously seen for biliary colic comes back w/severe pain that lasts longer, and travels to shoulder. Feeling sick: febrile, tachycardic, hypotensive, high WBC, tachypnic.
What is going on? What should you do?
- ACUTE COLECYSTITIS
- Stone trying to come out for longer period of time, and gallbladder distended, leading to inflammation (not the same as infection)
- These pts need to be admitted to hospital:
1. Give IV AB
2. Call surgeons -> gallbladder can rupture, leading to peritonitis, sepsis, and high rate of mortality