Gallstone disease pathophysiology: Difference between revisions

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[[Image:Gallstones.jpg|thumb|200px|left|[[Gall bladder]] opened to show numerous '''gallstones'''. Their brownish to greenish color suggest they are cholesterol [[Calculus (medicine)|calculi]]. Source: Wikimedia Commons<ref>name="urlFile:Gallensteine 2006 03 28.JPG - Wikimedia Commons">{{cite web |url=https://commons.wikimedia.org/wiki/File:Gallensteine_2006_03_28.JPG |title=File:Gallensteine 2006 03 28.JPG - Wikimedia Commons |format= |work= |accessdate=}}</ref>]]
[[Image:Gallstones.jpg|thumb|200px|left|[[Gall bladder]] opened to show numerous '''gallstones'''. Their brownish to greenish color suggest they are cholesterol [[Calculus (medicine)|calculi]]. Source: Wikimedia Commons<ref>name="urlFile:Gallensteine 2006 03 28.JPG - Wikimedia Commons">{{cite web |url=https://commons.wikimedia.org/wiki/File:Gallensteine_2006_03_28.JPG |title=File:Gallensteine 2006 03 28.JPG - Wikimedia Commons |format= |work= |accessdate=}}</ref>]]


Gallstones are hard, pebble-like structures that obstruct the cystic duct. The formation of gallstones is often preceded by the presence of biliary sludge, a viscous mixture of glycoproteins, calcium deposits, and cholesterol crystals in the gallbladder or biliary ducts.5 In the U.S., most gallstones consist largely of bile supersaturated with cholesterol.1,2 This hypersaturation, which results from the cholesterol concentration being greater than its solubility percentage, is caused primarily by hypersecretion of cholesterol due to altered hepatic cholesterol metabolism.1,3 A distorted balance between pronucleating (crystallization-promoting) and antinucleating (crystallization-inhibiting) proteins in the bile also can accelerate crystallization of cholesterol in the bile.1-3,5 Mucin, a glycoprotein mixture secreted by biliary epithelial cells, has been documented as a pronucleating protein. It is the decreased degradation of mucin by lysosomal enzymes that is believed to promote the formation of cholesterol crystals.3
It is thought that Gallstone disease is caused by bile hypersaturation, meaning that the bile becomes over saturated with a particular substance more than can be dissolved in the bile.  
 
One of the most important substances that can lead to stone formation is Cholesterol.
Loss of gallbladder muscular-wall motility and excessive sphincteric contraction also are involved in gallstone formation.1 This hypomotility leads to prolonged bile stasis (delayed gallbladder emptying), along with decreased reservoir function.3,5 The lack of bile flow causes an accumulation of bile and an increased predisposition for stone formation. Ineffective filling and a higher proportion of hepatic bile diverted from the gallbladder to the small bile duct can occur as a result of hypomotility.1,5
Cholesterol is an important substance that is needed to form cell membranes and to produce steroid hormones in the body.
 
Its quantity must be balanced internally and the only way in which the body can rid itself of it is through the bile.
Occasionally, gallstones are composed of bilirubin, a chemical that is produced as a result of the standard breakdown of RBCs. Infection of the biliary tract and increased enterohepatic cycling of bilirubin are the suggested causes of bilirubin stone formation. Bilirubin stones, often referred to as pigment stones, are seen primarily in patients with infections of the biliary tract or chronic hemolytic diseases (or damaged RBCs).1,3,6 Pigment stones are more frequent in Asia and Africa.3,6
The process of stone formation begins with the presence of biliary sludge.
 
This thick compound consists of glycoproteins, calcium deposits, and cholesterol crystals in the gallbladder.  
The pathogenesis of cholecystitis most commonly involves the impaction of gallstones in the bladder neck, Hartmann’s pouch, or the cystic duct; gallstones are not always present in cholecystitis, however.5 Pressure on the gallbladder increases, the organ becomes enlarged, the walls thicken, the blood supply decreases, and an exudate may form.2,5 Cholecystitis can be either acute or chronic, with repeated episodes of acute inflammation potentially leading to chronic cholecystitis. The gallbladder can become infected by various microorganisms, including those that are gas forming. An inflamed gallbladder can undergo necrosis and gangrene and, if left untreated, may progress to symptomatic sepsis.1,2,5 Failure to properly treat cholecystitis may result in perforation of the gallbladder, a rare but life-threatening phenomenon.2,5,7 Cholecystitis also can lead to gallstone pancreatitis if stones dislodge down to the sphincter of Oddi and are not cleared, thus blocking the pancreatic duct.1
This precipitation is also called "crystallization".    
 
Usually there are antagonistic mechanisms in place that work to prevent cholesterol from precipitating or crystallizing in the bile.
 
These include: pronucleating (crystallization-promoting) and antinucleating (crystallization-inhibiting) factors.
 
Furthermore, the lack of motility in the muscular wall of the gallbladder or the excessive sphincter contraction, that prevents bile secretion may also contribute to stone formation.  
It is thought that Gallstone disease is caused by bile hypersaturation.
This causes bile to stagnate within the gallbladder.
 
Rarely, the gallbladder may not properly fill with bile and so the bile is instead diverted from the gallbladder to the small bile duct.
 
This exacerbates the hypomotility and accelerates stone formation.  
 
Occasionally, gallstones are composed of bilirubin and can be referred to as "pigment stones".
 
Bilirubin is a byproduct of red blood cell breakdown.  
These stones are formed via two main pathways:
1. An infection of the biliary tract can predispose to stone formation.
2.Bile is normally recycled after its secretion back from the small bowel and to the liver. If there is increased enterohepatic cycling this may also cause the formation of a bilirubin stone. Pigment stones are seen more often in the Asian and African continents.






 


===Associated Conditions===  
===Associated Conditions===  

Revision as of 16:28, 28 November 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hadeel Maksoud M.D.[2]

Overview

It has long been noted that gallbladder stone formation is associated with bile supersaturation, and this still remains the most common cause for gallstone formation.[1]

Pathophysiology

Gall bladder opened to show numerous gallstones. Their brownish to greenish color suggest they are cholesterol calculi. Source: Wikimedia Commons[2]

It is thought that Gallstone disease is caused by bile hypersaturation, meaning that the bile becomes over saturated with a particular substance more than can be dissolved in the bile. One of the most important substances that can lead to stone formation is Cholesterol. Cholesterol is an important substance that is needed to form cell membranes and to produce steroid hormones in the body. Its quantity must be balanced internally and the only way in which the body can rid itself of it is through the bile. The process of stone formation begins with the presence of biliary sludge. This thick compound consists of glycoproteins, calcium deposits, and cholesterol crystals in the gallbladder. This precipitation is also called "crystallization". Usually there are antagonistic mechanisms in place that work to prevent cholesterol from precipitating or crystallizing in the bile. These include: pronucleating (crystallization-promoting) and antinucleating (crystallization-inhibiting) factors. Furthermore, the lack of motility in the muscular wall of the gallbladder or the excessive sphincter contraction, that prevents bile secretion may also contribute to stone formation. This causes bile to stagnate within the gallbladder. Rarely, the gallbladder may not properly fill with bile and so the bile is instead diverted from the gallbladder to the small bile duct. This exacerbates the hypomotility and accelerates stone formation. Occasionally, gallstones are composed of bilirubin and can be referred to as "pigment stones". Bilirubin is a byproduct of red blood cell breakdown. These stones are formed via two main pathways: 1. An infection of the biliary tract can predispose to stone formation. 2.Bile is normally recycled after its secretion back from the small bowel and to the liver. If there is increased enterohepatic cycling this may also cause the formation of a bilirubin stone. Pigment stones are seen more often in the Asian and African continents.



Associated Conditions

On the other hand, wine and whole grain bread may decrease the risk of gallstones.[5]

Gross Pathology

Gall bladder opened to show numerous gallstones. Source: Wikimedia Commons[6]



On gross pathology, multiple small stones are commonly found or less commonly a solitary stone is seen. The smaller stones represent a higher morbidity since they can easily occlude the biliary tracts.[7]

Microscopic Pathology

On microscopic histopathological analysis, variable evidences of inflammation can be noted transmurally including neutrophils, which are characteristic in gallstone disease.[8]

References

  1. Wang HH, Portincasa P, Wang DQ (2008). "Molecular pathophysiology and physical chemistry of cholesterol gallstones". Front. Biosci. 13: 401–23. PMID 17981556.
  2. name="urlFile:Gallensteine 2006 03 28.JPG - Wikimedia Commons">"File:Gallensteine 2006 03 28.JPG - Wikimedia Commons".
  3. Lv J, Yu C, Guo Y, Bian Z, Yang L, Chen Y, Li S, Huang Y, Fu Y, He P, Tang A, Chen J, Chen Z, Qi L, Li L (2017). "Gallstone Disease and the Risk of Type 2 Diabetes". Sci Rep. 7 (1): 15853. doi:10.1038/s41598-017-14801-2. PMID 29158491.
  4. R.M. Ortega (1997). "Differences in diet and food habits between patients with gallstones and controls". Journal of the American College of Nutrition. 16: 88–95. Unknown parameter |month= ignored (help); Unknown parameter |coauthors= ignored (help); |access-date= requires |url= (help)
  5. European Journal Gastroenterology & Hepatology. 6: 585–593. 1995. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  6. "File:Gallensteine 2006 03 28.JPG - Wikimedia Commons".
  7. Ansert, Sandra (2018). Textbook of diagnostic sonography. St. Louis, MO: Elsevier. ISBN 978-0323353755.
  8. Fisher, M. M. (1979). Gallstones. Boston, MA: Springer US. ISBN 1461570662.

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