Liver disease
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Liver disease, or hepatic disease, is any of many diseases of the liver.<ref name="medl">Template:Cite web</ref> If long-lasting it is termed chronic liver disease.<ref>Template:Cite web</ref> Although the diseases differ in detail, liver diseases often have features in common.
Signs and symptoms
Some of the signs and symptoms of a liver disease are the following:
- Jaundice<ref>Template:Cite web</ref>
- Confusion and altered consciousness caused by hepatic encephalopathy.<ref>Template:Cite web</ref>
- Thrombocytopenia and coagulopathy.<ref name="Blonski Siropaides Reddy 2007 pp. 464–73">Template:Cite journal</ref>
- Risk of bleeding symptoms, particularly taking place in the gastrointestinal tract<ref name="Tripodi Mannucci pp. 147–156">Template:Cite journal</ref>
Types
There are more than a hundred different liver diseases. Some of the most common are:<ref>Template:Cite web</ref>
- Fascioliasis, a parasitic infection of liver caused by a liver fluke of the genus FascioIa, mostly FascioIa hepatica.<ref>Template:Cite web</ref>
- Hepatitis, inflammation of the liver, is caused by various viruses (viral hepatitis) also by some liver toxins (e.g. alcoholic hepatitis), autoimmunity (autoimmune hepatitis) or hereditary conditions.<ref>Template:Cite web</ref>
- Alcoholic liver disease is a hepatic manifestation of alcohol overconsumption, including fatty liver disease, alcoholic hepatitis, and cirrhosis. Analogous terms such as "drug-induced" or "toxic" liver disease are also used to refer to disorders caused by various drugs.<ref>Template:MedlinePlusEncyclopedia</ref>
- Fatty liver disease (hepatic steatosis) is a reversible condition where large vacuoles of triglyceride fat accumulate in liver cells.<ref>Template:Cite web</ref> Non-alcoholic fatty liver disease is a spectrum of disease associated with obesity and metabolic syndrome.<ref>Template:Cite web</ref>
- Hereditary diseases that cause damage to the liver include hemochromatosis,<ref>Template:Cite web</ref> involving accumulation of iron in the body, and Wilson's disease. Liver damage is also a clinical feature of alpha 1-antitrypsin deficiency<ref>Template:Cite web</ref> and glycogen storage disease type II.<ref>Template:Cite book</ref>
- In transthyretin-related hereditary amyloidosis, the liver produces a mutated transthyretin protein which has severe neurodegenerative or cardiopathic effects. Liver transplantation can be curative.<ref>Template:Cite web</ref>
- Gilbert's syndrome, a genetic disorder of bilirubin metabolism found in a small percent of the population, can cause mild jaundice.<ref>Template:Cite web</ref>
- Cirrhosis is the formation of fibrous tissue (fibrosis) in the place of liver cells that have died due to a variety of causes, including viral hepatitis, alcohol overconsumption, and other forms of liver toxicity. Cirrhosis causes chronic liver failure.<ref>Template:Cite web</ref>
- Primary liver cancer most commonly manifests as hepatocellular carcinoma or cholangiocarcinoma; rarer forms include angiosarcoma and hemangiosarcoma of the liver. (Many liver malignancies are secondary lesions that have metastasized from primary cancers in the gastrointestinal tract and other organs, such as the kidneys, lungs.)<ref>Template:Cite web</ref>
- Primary biliary cirrhosis is a serious autoimmune disease of the bile capillaries.<ref>Template:Cite web</ref>
- Primary sclerosing cholangitis is a serious chronic inflammatory disease of the bile duct, which is believed to be autoimmune in origin.<ref>Template:Cite web</ref>
- Budd–Chiari syndrome is the clinical picture caused by occlusion of the hepatic vein.<ref>Template:Cite web</ref>
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Ground glass hepatocytes
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Primary biliary cirrhosis
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Budd–Chiari syndrome
Mechanisms
Liver diseases can develop through several mechanisms:
DNA damage
One general mechanism, increased DNA damage, is shared by some of the major liver diseases, including infection by hepatitis B virus or hepatitis C virus, heavy alcohol consumption, and obesity.<ref name="urlChronic Liver Disease/Cirrhosis | Johns Hopkins Medicine Health Library">Template:Cite web</ref>
Viral infection by hepatitis B virus, or hepatitis C virus causes an increase of reactive oxygen species. The increase in intracellular reactive oxygen species is about 10,000-fold with chronic hepatitis B virus infection and 100,000-fold following hepatitis C virus infection.<ref name="enomoto">Template:Cite journal</ref> This increase in reactive oxygen species causes inflammation<ref name=enomoto/> and more than 20 types of DNA damage.<ref name="pmid27989142">Template:Cite journal</ref> Oxidative DNA damage is mutagenic<ref name="pmid22293091">Template:Cite journal</ref> and also causes epigenetic alterations at the sites of DNA repair.<ref name=Nishida>Template:Cite journal</ref> Epigenetic alterations and mutations affect the cellular machinery that may cause the cell to replicate at a higher rate or result in the cell avoiding apoptosis, and thus contribute to liver disease.<ref name="pmid24473361">Template:Cite journal</ref> By the time accumulating epigenetic and mutational changes eventually cause hepatocellular carcinoma, epigenetic alterations appear to have an even larger role in carcinogenesis than mutations. Only one gene, TP53, is mutated in more than 20% of liver cancers while 41 genes each have hypermethylated promoters (repressing gene expression) in more than 20% of liver cancers.<ref name="pmid23392071">Template:Cite journal</ref>
Alcohol consumption in excess causes a build-up of acetaldehyde. Acetaldehyde and free radicals generated by metabolizing alcohol induce DNA damage and oxidative stress.<ref name="pmid20813101">Template:Cite journal</ref><ref name=Lee>Template:Cite journal</ref><ref name="urlDrinking alcohol causes cancer by damaging DNA - Independent.ie">Template:Cite web</ref> In addition, activation of neutrophils in alcoholic liver disease contributes to the pathogenesis of hepatocellular damage by releasing reactive oxygen species (which can damage DNA).<ref name="pmid22524187">Template:Cite journal</ref> The level of oxidative stress and acetaldehyde-induced DNA adducts due to alcohol consumption does not appear sufficient to cause increased mutagenesis.<ref name="pmid22524187"/> However, as reviewed by Nishida et al.,<ref name=Nishida /> alcohol exposure, causing oxidative DNA damage (which is repairable), can result in epigenetic alterations at the sites of DNA repair. Alcohol-induced epigenetic alterations of gene expression appear to lead to liver injury and ultimately carcinoma.<ref name="pmid24313164">Template:Cite journal</ref>
Obesity is associated with a higher risk of primary liver cancer.<ref name="pmid27909908">Template:Cite book</ref> As shown with mice, obese mice are prone to liver cancer, likely due to two factors. Obese mice have increased pro-inflammatory cytokines. Obese mice also have higher levels of deoxycholic acid, a product of bile acid alteration by certain gut microbes, and these microbes are increased with obesity. The excess deoxycholic acid causes DNA damage and inflammation in the liver, which, in turn, can lead to liver cancer.<ref name="urlGut Bugs Could Explain Obesity-Cancer Link | Science | AAAS">Template:Cite web</ref>
Other relevant aspects
Several liver diseases are due to viral infection. Viral hepatitides such as Hepatitis B virus and Hepatitis C virus can be vertically transmitted during birth via contact with infected blood.<ref name=Benova2014>Template:Cite journal</ref><ref name=Komatsu2014>Template:Cite journal</ref> According to a 2012 NICE publication, "about 85% of hepatitis B infections in newborns become chronic".<ref>Template:Cite web</ref> In occult cases, Hepatitis B virus is present by hepatitis B virus DNA, but testing for HBsAg is negative.<ref>Template:Cite journal</ref> High consumption of alcohol can lead to several forms of liver disease including alcoholic hepatitis, alcoholic fatty liver disease, cirrhosis, and liver cancer.<ref name=Suk2014>Template:Cite journal</ref> In the earlier stages of alcoholic liver disease, fat builds up in the liver's cells due to increased creation of triglycerides and fatty acids and a decreased ability to break down fatty acids.<ref name=Williams2014>Template:Cite journal</ref> Progression of the disease can lead to liver inflammation from the excess fat in the liver. Scarring in the liver often occurs as the body attempts to heal and extensive scarring can lead to the development of cirrhosis in more advanced stages of the disease.<ref name=Williams2014/> Approximately 3–10% of individuals with cirrhosis develop a form of liver cancer known as hepatocellular carcinoma.<ref name=Williams2014/> According to Tilg, et al., gut microbiome could very well have an effect, be involved in the pathophysiology, on the various types of liver disease which an individual may encounter.<ref>Template:Cite journal</ref> Insight into the exact causes and mechanisms mediating pathophysiology of the liver is quickly progressing due to the introduction new technological approaches like Single cell sequencing and kinome profiling <ref>Template:Cite journal</ref>
Air pollutants
Particulate matter or carbon black are common pollutants. They have a direct toxic effect on the liver; cause inflammation of liver caused by and thereby impact lipid metabolism and fatty liver disease; and can translocate from the lungs to the liver.<ref name="kim">Template:Cite journal</ref>
Because particulate matter and carbon black are very diverse and each has different toxicodynamics, detailed mechanisms of translocation are not clear. Water-soluble fractions of particulate matter are the most important part of translocation to the liver, through extrapulmonary circulation. When particulate matter gets into the bloodstream, it combines with immune cells and stimulates innate immune responses. Pro-inflammatory cytokines are released and cause disease progression.<ref name=kim/>
Diagnosis
A number of liver function tests are available to test the proper function of the liver. These test for the presence of enzymes in blood that are normally most abundant in liver tissue, metabolites or products. serum proteins, serum albumin, serum globulin, alanine transaminase, aspartate transaminase, prothrombin time, partial thromboplastin time.<ref name="web">Template:MedlinePlusEncyclopedia</ref>
Imaging tests such as transient elastography, ultrasound and magnetic resonance imaging can be used to show the liver tissue and the bile ducts. Liver biopsy can be performed to examine liver tissue to distinguish between various conditions; tests such as elastography may reduce the need for biopsy in some situations.<ref>Template:Cite journal</ref>
In liver disease, prothrombin time is longer than usual.<ref name="Blonski Siropaides Reddy 2007 pp. 464–73"/> In addition, the amounts of both coagulation factors and anticoagulation factors are reduced as a diseased liver cannot productively synthesize them as it did when healthy.<ref name="Barton 2016 pp. 1927–1933">Template:Cite journal</ref> Nonetheless, there are two exceptions in this falling tendency: coagulation factor VIII and von Willebrand factor, a platelet adhesive protein.<ref name="Barton 2016 pp. 1927–1933"/> Both inversely rise in the setting of hepatic insufficiency, thanks to the drop of hepatic clearance and compensatory productions from other sites of the body.<ref name="Barton 2016 pp. 1927–1933"/> Fibrinolysis generally proceeds faster with acute liver failure and advanced stage liver disease, unlike chronic liver disease in which concentration of fibrinogen remains unchanged.<ref name="Barton 2016 pp. 1927–1933"/>
A previously undiagnosed liver disease may become evident first after autopsy.Template:Citation needed Following are gross pathology images:
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Diffuse cirrhosis
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Macronodular cirrhosis
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Nutmeg texture of congestive hepatopathy
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Treatment
Anti-viral medications are available to treat infections such as hepatitis B.<ref>Template:Cite journal</ref> Other conditions may be managed by slowing down disease progression, for example:
- By using steroid-based drugs in autoimmune hepatitis.<ref>Template:Cite book</ref>
- Regularly removing a quantity of blood from a vein (venesection) in the iron overload condition, hemochromatosis.<ref>Template:Cite web</ref>
- Wilson's disease, a condition where copper builds up in the body, can be managed with drugs that bind copper, allowing it to be passed from the body in urine.<ref>Template:Cite web</ref>
- In cholestatic liver disease, (where the flow of bile is affected due to cystic fibrosis<ref>Template:Cite book</ref>) a medication called ursodeoxycholic acid may be given.<ref>Template:Cite journal</ref>
Epidemiology
Template:Owidslider Liver diseases, including conditions such as non-alcoholic fatty liver disease (NAFLD), alcohol-related liver disease (ALD), and viral hepatitis, are significant public health concerns worldwide. In the United States, NAFLD is the most common chronic liver condition, affecting approximately 24% of the population, with the prevalence rising due to increasing rates of obesity and metabolic syndrome.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Alcohol-related liver disease accounts for about 4.5% of liver-related deaths globally, underscoring the substantial burden of alcohol misuse.<ref>Template:Cite journal</ref> Viral hepatitis, primarily hepatitis B and hepatitis C, remains a leading cause of liver cirrhosis and liver cancer worldwide, despite advances in antiviral therapies and vaccination efforts.<ref>Template:Cite journal</ref> Additionally, recent studies have highlighted lean steatotic liver disease (SLD), a subset of NAFLD, affecting over 12% of U.S. adults even in the absence of obesity.<ref>Template:Cite journal</ref> These data emphasize the importance of early detection and targeted interventions to manage liver disease and its associated complications effectively.
New research reports the prevalence of lean steatotic liver disease (SLD) in the United States using data from the National Health and Nutrition Examination Survey (2017-2023), researchers estimated the age-adjusted prevalence of lean SLD at 12.8%.<ref>Template:Cite journal</ref> This includes 9.3% for lean metabolic dysfunction-associated steatotic liver disease, 1.3% for metabolic dysfunction and alcohol-related steatotic liver disease, and 1.0% for alcohol-related liver disease.<ref>Template:Cite web</ref>