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Medical condition From Wikipedia, the free encyclopedia
Alcoholic hepatitis is hepatitis (inflammation of the liver) due to excessive intake of alcohol.[2] Patients typically have a history of at least 10 years of heavy alcohol intake, typically 8–10 drinks per day.[3] It is usually found in association with fatty liver, an early stage of alcoholic liver disease, and may contribute to the progression of fibrosis, leading to cirrhosis. Symptoms may present acutely after a large amount of alcoholic intake in a short time period, or after years of excess alcohol intake. Signs and symptoms of alcoholic hepatitis include jaundice (yellowing of the skin and eyes), ascites (fluid accumulation in the abdominal cavity), fatigue and hepatic encephalopathy (brain dysfunction due to liver failure).[3] Mild cases are self-limiting, but severe cases have a high risk of death. Severity in alcoholic hepatitis is determined several clinical prediction models such as the Maddrey's Discriminant Function and the MELD score.
| Alcoholic hepatitis | |
|---|---|
| |
| Micrograph showing a Mallory body, a histopathologic finding associated with alcoholic hepatitis. H&E stain. | |
| Specialty | Gastroenterology |
| Complications | Cirrhosis, kidney failure, confusion, drowsiness and slurred speech (hepatic encephalopathy), ascites, enlarged veins (varices)[1] |
| Risk factors | Sex, obesity, genetic factors, race and ethnicity, binge drinking[1] |
Severe cases may be treated with glucocorticoids with a response rate of about 60%. The condition often comes on suddenly and may progress in severity very rapidly.
Alcoholic hepatitis is characterized by a number of symptoms, which may include feeling unwell, enlargement of the liver, development of fluid in the abdomen (ascites), and modest elevation of liver enzyme levels (as determined by liver function tests).[4] It may also present with Hepatic encephalopathy (brain dysfunction due to liver failure) causing symptoms such as confusion, decreased levels of consciousness, or asterixis,[5] (a characteristic flapping movement when the wrist is extended indicative of hepatic encephalopathy). Severe cases are characterized by profound jaundice, obtundation (ranging from drowsiness to unconsciousness), and progressive critical illness; the mortality rate is 50% within 30 days of onset despite best care.[3]
Alcoholic hepatitis is distinct from cirrhosis caused by long-term alcohol consumption. Alcoholic hepatitis can occur in patients with chronic alcoholic liver disease and alcoholic cirrhosis. Alcoholic hepatitis by itself does not lead to cirrhosis, but cirrhosis is more common in patients with long term alcohol consumption.[6] Some alcoholics develop acute hepatitis as an inflammatory reaction to the cells affected by fatty change.[6] This is not directly related to the dose of alcohol. Some people seem more prone to this reaction than others. This inflammatory reaction to the fatty change is called alcoholic steatohepatitis and the inflammation probably predisposes to liver fibrosis by activating hepatic stellate cells to produce collagen.[6]
The pathological mechanisms in alcoholic hepatitis are incompletely understood but a combination of direct hepatocyte damage by alcohol and its metabolites in addition to increased intestinal permeability are thought to play a role.[7] Heavy alcohol consumption increases intestinal permeability by causing direct damage to enterocytes (intestinal absorptive cells) and causing disruptions of tight junctions that form a barrier between the enterocytes.[7] This leads to increased intestinal permeability which then leads to pathogenic gut bacteria (such as enterococcus faecalis) or immunogenic fungi entering the portal circulation, and travelling to the liver where they cause hepatocyte damage.[7] In the case of enterococcus faecalis, the bacterium can release an exotoxin which is directly damaging to liver cells.[7] Chronic alcohol consumption may alter the gut microbiome and promote the production of these pathogenic bacteria.[7] Many of these pathogenic bacteria also contain Pathogen Associated Molecular Patterns (PAMPs), extracellular motifs that are recognized by the immune system as foreign material, which may lead to an exaggerated inflammatory response in the liver which further leads to hepatocyte damage.[7]
Alcohol is also directly damaging to liver cells. Alcohol is metabolized to acetaldehyde in the liver via the enzymes CYP2E1 and aldehyde dehydrogenase.[7] Acetaldehyde forms reactive oxygen species in the liver as well as acting as a DNA adduct (binding to DNA) leading to direct hepatocyte damage.[7] This manifests as lipid peroxidation, mitochondrial damage, and glutathione (an endogenous antioxidant) depletion.[7] Damaged hepatocytes release Danger associated molecular patterns (DAMPs) which are molecules that lead to further activation of the immune system's inflammatory response and further hepatocyte damage.[7]
The chronic inflammation seen in alcoholic hepatitis leads to a distinctive fibrotic response, with fibrogenic cell type activation. This occurs via an increased extracellular matrix deposition around hepatocytes and sinusoidal cells which causes a peri-cellular fibrosis known as "chickenwire fibrosis".[7] This peri-cellular chickenwire fibrosis leads to portal hypertension or an elevated blood pressure in the portal veins that drain blood from the intestines to the liver.[7] This causes many of the sequelae of chronic liver disease including esophageal varices (with associated variceal bleeding), ascites and splenomegaly.
The chronic inflammation seen in alcoholic hepatitis also leads to impaired hepatocyte differentiation, impairments in hepatocyte regeneration and hepatocyte de-differentiation into cholangiocyte type cells.[7] This leads to defects in the liver's many functions including impairments in bilirubin transport, clotting factor synthesis, glucose metabolism and immune dysfunction.[7] This impaired compensatory liver regenerative response further leads to a ductular reaction; a type of abnormal liver cell architecture.[7]
Due to the release of DAMPs and PAMPs, an acute systemic inflammatory state can develop after extensive alcohol intake that dominates the clinical landscape of acute severe alcoholic hepatitis. IL-6 has been shown to have the most robust increase among pro-inflammatory mediators in these patients. Furthermore, decreased levels of IL-13, an antagonistic cytokine of IL-6 was found to be closely associated with short-term (90-day) mortality in severe alcoholic hepatitis patients.[8]
Some signs and pathological changes in liver histology include:
If chronic liver disease is also present:
The diagnosis is made in a patient with history of significant alcohol intake who develops worsening liver function tests, including elevated bilirubin (typically greater than 3.0) and aminotransferases, and onset of jaundice within the last 8 weeks.[3] The ratio of aspartate aminotransferase to alanine aminotransferase is usually 2 or more.[13] In most cases, the liver enzymes do not exceed 500. A liver biopsy is not required for the diagnosis, however it can help confirm alcoholic hepatitis as the cause of the hepatitis if the diagnosis is unclear.[3][14]
Clinical practice guidelines have recommended corticosteroids.[15]
People should be risk stratified using a MELD Score or Child-Pugh score. These scores are used to evaluate the severity of the liver disease based on several lab values. The greater the score, the more severe the disease.
Females are more susceptible to alcohol-associated liver injury and are therefore at higher risk of alcohol-associated hepatitis.[7] Certain genetic variations in the PNPLA3-encoding gene, which codes for an enzyme involved in triglyceride metabolism in adipose tissue are thought to influence disease severity.[7] Other factors in alcoholic hepatitis associated with a poor prognosis include concomitant hepatic encephalopathy and acute kidney injury.[7]
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