Liver

Question 1

Brown pigment stones

Answer 1

Radiolucent. Biliary tract infection. Commonly seen in Asians.

Question 2

Gallstone classification

Answer 2

Cholesterol stones, pigment stones, mixed stones

Question 3

Black pigment stones

Answer 3

Radio-opaque (appear on x-ray) because they contain high amounts of calcium carbonate and phosphates. Calcium bilirubinate + calcium carbonate.

Chronic extravascular hemolysis - when increased unconjugated bilirubin precipitates in bile as calcium bilirubinate.

Small, spiculated, crumbly.

Question 4

Black versus brown pigment stones - radiolucent or opaque?

Answer 4

Black: radio-opaque, brown: radio-lucent.

Question 5

7alpha hydroxylase

Answer 5

Converts cholesterol into bile acids.

Suppressed by fibrates (benzafibrate, fenofibrate, ciprofibrate).

If this is suppressed, increased concentration of cholesterol in bile. When gallbladder is hypomotile or there is more cholesterol than can dissolve, cholesterol precipitates into insoluble crystals. These eventually make gallstones.

Question 6

Cholesterol stones

Answer 6

Radiolucent with 10-20% opaque due to calcium carbonate. Usually stones of mixed composition. Stones contain CH, Calcium carbonate, some bilirubin pigment.

80% of gallstones.

Associated with:

• obesity
• Crohn’s Disease
• CF
• Advanced age
• Clofibrate
• Estrogen therapy
• Multiparity
• Rapid wt loss
• Native American origin

REMEMBER: RISK FACTORS - THE 4 FS:

• FEMALE
• FORTY
• FAT
• FERTILE (PREGNANT)

Question 7

HMG-CoA reductase

Answer 7

Necessary for cholesterol biosynthesis; specifically catalyzes the HMG-CoA to mevalonate reaction. So decreased functionality of this enzyme would decrease cholesterol biosynthesis and discourage cholesterol gallstone formation.

Question 8

Estrogen and cholesterol biosynthesis

Answer 8

Estrogen increases hepatic HMG-CoA reductase activity.

Thus, OCPs are a risk factor for cholesterol gallstones.

Question 9

Aromatase and cholesterol biosynthesis

Answer 9

Aromatase catalyzes androgen –> estrogen conversion.

Estrogen increases hepatic HMG-CoA reductase activity. OCPs are a risk factor for cholesterol gallstones.

Question 10

Beta-glucoronidase

Answer 10

Deconjugates bilirubin. Bilirubin glucuronides get hydrolyzed. Associated with brown pigment stones - injured hepatocytes release beta glucuronidase and unconjugated bilirubin in the bile increases.

Question 11

Biliary sludge

Answer 11

Typically contains cholesterol monohydrate crystals, calcium bilirubinate, and mucus. Known precursor to stone formation.

Question 12

Components of bile

Answer 12

Bile salts and acids - 67% 
Phospholipid - 22% (mainly lecithin)
Protein - 4.5%
Free cholesterol - 4%
Conjugated bilirubin - 0.3%