Metabolisme Batu Empedu

8/10/2019 Metabolisme Batu Empedu

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Metabolisme batu empedu


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Epidemiologi

the third National Health and Nutrition

Examination Survey (NHANES III) has revealed

an overall prevalence of gallstones of 7.9% in

men and 16.6% in women. The prevalence

was high in Mexican Americans (8.9% in men,

26.7% in women), intermediate for non-

Hispanic whites (8.6% in men, 16.6% inwomen), and low for African Americans (5.3%

in men, 13.9% in women).


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Epidemiologi


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Patogenesis

Gallstones are formed because of abnormal bilecomposition.

They are divided into two major types:

cholesterol stones (80%) : Cholesterol gallstones usuallycontain >50% cholesterol monohydrate plus anadmixture of calcium salts, bile pigments, and proteins.

pigment stone (20%) : Pigment stones are composed

primarily of calcium bilirubinate; they contain


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cholesterol gallstone disease occurs because of

several defects, which include (1) bile

supersaturation with cholesterol, (2)

nucleation of cholesterol monohydrate with

subsequent crystal retention and stone

growth, and (3) abnormal gallbladder motor

function with delayed emptying and stasis


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Pigment stones

Black pigment stones are composed of either pure

calcium bilirubinate or polymer-like complexes

with calcium and mucin glycoproteins.

Brown pigment stones are composed of calcium

salts of unconjugated bilirubin with varying

amounts of cholesterol and protein.

Pigment stone formation is especially prominent inAsians and is often associated with infections in

the gallbladder and biliary tree


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Table 311-1 Predisposing Factors for Cholesterol and Pigment Gallstone Formation

Cholesterol Stones

1. Demographic/genetic factors: Prevalence highest in North American Indians, Chilean Indians, and Chilean Hispanics, greater in Northern Europe and North

America than in Asia, lowest in Japan; familial disposition; hereditary aspects

2. Obesity, metabolic syndrome: Normal bile acid pool and secretion but increased biliary secretion of cholesterol3. Weight loss: Mobilization of tissue cholesterol leads to increased biliary cholesterol secretion while enterohepatic circulation of bile acids is decreased

4. Female sex hormones

a. Estrogens stimulate hepatic lipoprotein receptors, increase uptake of dietary cholesterol, and increase biliary cholesterol secretion

b. Natural estrogens, other estrogens, and oral contraceptives lead to decreased bile salt secretion and decreased conversion of cholesterol to cholesteryl esters

5. Increasing age: Increased biliary secretion of cholesterol, decreased size of bile acid pool, decreased secretion of bile salts

6. Gallbladder hypomotility leading to stasis and formation of sludge

a. Prolonged parenteral nutrition

b. Pregnancyc. Fasting

d. Drugs such as octreotide

7. Clofibrate therapy: Increased biliary secretion of cholesterol

8. Decreased bile acid secretion

a. Primary biliary cirrhosis

b. Genetic defect of the CYP7A1gene

9. Decreased phospholipid secretion: Genetic defect of the MDR3gene

10. Miscellaneous

a. High-calorie, high-fat dietb. Spinal cord injury

Pigment Stones

1. Demographic/genetic factors: Asia, rural setting

2. Chronic hemolysis

3. Alcoholic cirrhosis

4. Pernicious anemia

5. Cystic fibrosis

6. Chronic biliary tract infection, parasite infections

7. Increasing age8. Ileal disease, ileal resection or bypass


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Diagnostic Evaluation of the

Gallbladder

Diagnostic Advantages Diagnostic

Limitations

Comment

Gallbladder Ultrasound

RapidAccurate identification of gallstones

(>95%)

Simultaneous scanning of GB, liver, bile

ducts, pancreas

"Real-time" scanning allows assessment of

GB volume, contractility

Not limited by jaundice, pregnancy

May detect very small stones

Bowel gasMassive obesity

Ascites

Procedure of choice fordetection of stones


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Diagnosis advantages Diagnosis limitations comments

Plain Abdominal x-ray

Low cost Relatively low yield Pathognomonic findings in: calcified

gallstones

Readily available ? Contraindicated in pregnancy Limey bile, porcelain GB

Emphysematous cholecystitisGallstone ileus

Radioisotope Scans (HIDA, DIDA, etc.)

Accurate identification of cystic

duct obstruction

? Contraindicated in pregnancy Indicated for confirmation of suspected

acute cholecystitis; less sensitive and

less specific in chronic cholecystitis;

useful in diagnosis of acalculouscholecystopathy, especially if given with

CCK to assess gallbladder emptying

Simultaneous assessment of bile

ducts

Serum bilirubin >103205

mol/L (612 mg/dL)

Cholecystogram of lowresolution

Diagnostic Evaluation of the

Gallbladder


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Examples of ultrasound and radiologic studies of the biliary tract. A. An ultrasound study showing a distended

gallbladder containing a single large stone (arrow), which casts an acoustic shadow. B. Endoscopic retrograde

cholangiopancreatogram (ERCP) showing normal biliary tract anatomy. In addition to the endoscope and large

vertical gallbladder filled with contrast dye, the common hepatic duct (CHD), common bile duct (CBD), and

pancreatic duct (PD) are shown. The arrow points to the ampulla of Vater. C. Endoscopic retrograde cholangiogram

(ERC) showing choledocholithiasis. The biliary tract is dilatated and contains multiple radiolucent calculi. D. ERCP

showing sclerosing cholangitis. The common bile duct shows areas that are strictured and narrowed.


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Symptoms of Gallstone Disease

biliary colic (a constant and often long-lasting pain, colic begins quite

suddenly and may persist with severe intensity for 15 min to 5 h,

subsiding gradually or rapidly)

Nausea and vomitingepigastric fullness, dyspepsia, eructation, or flatulence, especially

following a fatty meal


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jaundice


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Jaundice, or icterus, is a yellowish

discoloration of tissue resulting from the

deposition of bilirubin. Tissue deposition of

bilirubin occurs only in the presence of serumhyperbilirubinemia and is a sign of either liver

disease or, less often, a hemolytic disorder


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Production and Metabolism of

Bilirubin

heme

Enzymheme

oxygenase

biliverdin

Enzymbiliverdinreduktase

Unconjugated

bilirubin (insolublein water)

Bound to albumin

Transportedto liver

bilirubin issolubilized byconjugation toglucuronic acid

Excreted into biledrains intoduodenum

hydrolyzed tounconjugated

bilirubin bybacterial -glucuronidases.Unconjugated

bilirubin

reducedbynormalgutbacteria

urobilinogen


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hiperbilirubinemia

The bilirubin present in serum represents a

balance between input from production of

bilirubin and hepatic/biliary removal of the

pigment. Hyperbilirubinemia may result from(1) overproduction of bilirubin; (2) impaired

uptake, conjugation, or excretion of bilirubin;

or (3) regurgitation of unconjugated orconjugated bilirubin from damaged

hepatocytes or bile ducts


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Metabolisme Batu Empedu

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