Short theoretic material - Гастроэнтерология (анг,рус) - Конспект лекций
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Гастроэнтерология (анг,рус)

Short theoretic material

 

Gallstone formation is the most common disorder of the biliary tree.

 

Pathology

n            Gallstones are conveniently classified into cholesterol or pigment stones, although the majority are of mixed composition.

n            Cholesterol stones are most common in industrialised countries, whereas pigment stones are more frequent in developing countries.

n            Gallstones contain varying quantities of calcium salts, including calcium bilirubinate, carbonate, phosphate and palmitate, which are radio-opaque.

 

Epidemiology

n            In Western countries gallstones are common and occur in 7% of males and 15% of females aged 18-65 years, with an overall prevalence of 11%.

n            In those under 40 years there is a 3:1 female preponderance, whereas in the elderly the sex ratio is about equal.

n            Gallstones are common in North America, Europe and Australia, and are less frequent in India, the Far East and Africa.

n            In developed countries the incidence of symptomatic gallstones appears to be increasing and they occur at an earlier age.

 

Pathogenesis

n            In gallstone disease the liver produces bile which contains an excess of cholesterol either because there is a relative deficiency of bile salts or a relative excess of cholesterol.

n            Such bile, which is supersaturated with cholesterol, is termed 'lithogenic'.

 

PATHOGENIC FACTORS LEADING TO THE PRODUCTION OF LITHOGENIC BILE

 

 

 

 

 

 

n            Factors initiating crystallisation of cholesterol in lithogenic bile (nucleation factors) are also important; patients with cholesterol gallstones have gallbladder bile which forms cholesterol crystals more rapidly than equally saturated bile from patients who do not form gallstones.

n            Factors favouring nucleation (mucus, calcium, fatty acids, other proteins) and antinucleating factors (apolipoproteins) have been described.

 

Cholesterol stones

n            Gallstone formation is multifactorial, and the factors involved are related to the type of gallstone.

n            Cholesterol is held in solution in bile by its association with bile acids and phospholipids in the form of micelles and vesicles.

n            Biliary lipoproteins may also have a role in solubilising cholesterol.

 

 

 

 

 

Risk factors and mechanisms for cholesterol gallstones

  ↑ Cholesterol secretion 

Elderly

Female

Pregnancy

Obesity

Rapid weight los

Impaired gallbladder emptying

Pregnancy

Gallbladder stasis

Fasting

Total parenteral nutrition

Spinal cord injury

↓ Bale salt secretion 

Pregnancy

 

Pigment stones

n            Brown crumbly pigment stones are almost always the consequence of bacterial or parasitic infection in the biliary tree.

n            They are found commonly in the Far East where infection of the biliary tree allows bacterial                  β-glucuronidase to hydrolyse conjugated bilirubin to its free form, which then precipitates as calcium bilirubinate.

n            The mechanism of black pigment gallstone formation in developed countries is not satisfactorily explained. Haemolysis is important as these stones occur in chronic haemolytic disease.

 

 

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