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Fatty liver disease (FLD), also known as hepatic steatosis, is a condition where excess
fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...
builds up in the
liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
. Often there are no or few symptoms. Occasionally there may be tiredness or pain in the upper right side of the
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
. Complications may include
cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...
,
liver cancer Liver cancer (also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy) is cancer that starts in the liver. Liver cancer can be primary (starts in liver) or secondary (meaning cancer which has spread from elsewhere to th ...
, and
esophageal varices Esophageal varices are extremely dilated sub-mucosal veins in the lower third of the esophagus. They are most often a consequence of portal hypertension, commonly due to cirrhosis. People with esophageal varices have a strong tendency to develop ...
. There are two types of fatty liver disease:
non-alcoholic fatty liver disease Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. There are two types; non-alcoholic ...
(NAFLD) and
alcoholic liver disease Alcoholic liver disease (ALD), also called alcohol-related liver disease (ARLD), is a term that encompasses the liver manifestations of alcohol overconsumption, including fatty liver, alcoholic hepatitis, and chronic hepatitis with liver fibrosis ...
. NAFLD is made up of
simple fatty liver Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. There are two types; non-alcoholic ...
and
non-alcoholic steatohepatitis Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. There are two types; non-alcoholic ...
(NASH). The primary risks include alcohol,
type 2 diabetes Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urinatio ...
, and
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
. Other risk factors include certain medications such as
glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
s, and
hepatitis C Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis. During the initial infection people often have mild or no symptoms. Occasionally a fever, dark urine, a ...
. It is unclear why some people with NAFLD develop simple fatty liver and others develop NASH. Diagnosis is based on the
medical history The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient is information gained by a physician by asking specific questions, either to the patient or to other peo ...
supported by blood tests,
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
, and occasionally
liver biopsy Liver biopsy is the biopsy (removal of a small sample of tissue) from the liver. It is a medical test that is done to aid diagnosis of liver disease, to assess the severity of known liver disease, and to monitor the progress of treatment. Medica ...
. Treatment of NAFLD is generally by dietary changes and exercise to bring about
weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other conn ...
. In those who are severely affected, liver transplantation may be an option. More than 90% of heavy drinkers develop fatty liver while about 25% develop the more severe
alcoholic hepatitis Alcoholic hepatitis is hepatitis (inflammation of the liver) due to excessive intake of alcohol. Patients typically have a history of at least 10 years of heavy alcohol intake, typically 8-10 drinks per day. It is usually found in association with ...
. NAFLD affects about 30% of people in Western countries and 10% of people in Asia. NAFLD affects about 10% of children in the United States. It occurs more often in older people and males.


Signs and symptoms

Often there are no or few symptoms. Occasionally there may be tiredness or pain in the upper right side of the abdomen.


Complications

Fatty liver can develop into a fibrosis or a liver cancer. For people affected by NAFLD, the 10-year survival rate was about 80%. The rate of progression of fibrosis is estimated to be one per 7 years in NASH and one per 14 years in NAFLD, with an increasing speed. There is a strong relationship between these pathologies and metabolic illnesses (diabetes type II, metabolic syndrome). These pathologies can also affect non-obese people, who are then at a higher risk. Less than 10% of people with cirrhotic alcoholic FLD will develop
hepatocellular carcinoma Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. It occurs in t ...
, the most common type of primary liver cancer in adults, but up to 45% people with NASH without cirrhosis can develop hepatocellular carcinoma. The condition is also associated with other diseases that influence fat
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
.


Causes

Fatty liver (FL) is commonly associated with
metabolic syndrome Metabolic syndrome is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Metabolic syndrome ...
(
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
,
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
, and
dyslipidemia Dyslipidemia is an abnormal amount of lipids (e.g. triglycerides, cholesterol and/or fat phospholipids) in the blood. Dyslipidemia is a risk factor for the development of atherosclerotic cardiovascular disease ( ASCVD). ASCVD includes coronary ar ...
), but can also be due to any one of many causes: ;Alcohol:
Alcohol use disorder Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomin ...
is one of the causes of fatty liver due to production of toxic metabolites like aldehydes during metabolism of alcohol in the liver. This phenomenon most commonly occurs with chronic alcohol use disorder. ;Metabolic:
abetalipoproteinemia Abetalipoproteinemia (also known as: Bassen-Kornzweig syndrome, microsomal triglyceride transfer protein deficiency disease, MTP deficiency, and betalipoprotein deficiency syndrome) is a disorder that interferes with the normal absorption of fat ...
, glycogen storage diseases,
Weber–Christian disease Weber–Christian disease, is a cutaneous condition characterized by recurrent subcutaneous nodules that heal with depression of the overlying skin. It is a type of panniculitis. It is a rare disease seen in females 30–60 years of age. It is a ...
,
acute fatty liver of pregnancy Acute fatty liver of pregnancy is a rare life-threatening complication of pregnancy that occurs in the third trimester or the immediate period after delivery. It is thought to be caused by a disordered metabolism of fatty acids by mitochondria in ...
,
lipodystrophy Lipodystrophy syndromes are a group of genetic or acquired disorders in which the body is unable to produce and maintain healthy fat tissue. The medical condition is characterized by abnormal or degenerative conditions of the body's adipose tissue. ...
;Nutritional:
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
,
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues a ...
,
total parenteral nutrition Parenteral nutrition (PN) is the feeding of nutritional products to a person intravenously, bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding companies. The person receives a nutritional mix ...
, severe
weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other conn ...
, refeeding syndrome,
jejunoileal bypass Jejunoileal bypass (JIB) was a surgical weight-loss procedure performed for the relief of morbid obesity from the 1950s through the 1970s in which all but 30 cm (12 in) to 45 cm (18 in) of the small bowel were detached and set ...
,
gastric bypass Gastric bypass surgery refers to a technique in which the stomach is divided into a small upper pouch and a much larger lower "remnant" pouch and then the small intestine is rearranged to connect to both. Surgeons have developed several differ ...
, jejunal
diverticulosis Diverticulosis is the condition of having multiple pouches (diverticulum, diverticula) in the colon (anatomy), colon that are not inflamed. These are outpockets of the colonic mucosa and submucosa through weaknesses of muscle layers in the col ...
with
bacterial overgrowth Small intestinal bacterial overgrowth (SIBO), also termed bacterial overgrowth, or small bowel bacterial overgrowth syndrome (SBBOS), is a disorder of excessive bacterial growth in the small intestine. Unlike the colon (or large bowel), which is r ...
;Drugs and toxins:
amiodarone Amiodarone is an antiarrhythmic medication used to treat and prevent a number of types of cardiac dysrhythmias. This includes ventricular tachycardia (VT), ventricular fibrillation (VF), and wide complex tachycardia, as well as atrial fibrilla ...
,
methotrexate Methotrexate (MTX), formerly known as amethopterin, is a chemotherapy agent and immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancies. Types of cancers it is used for include breast cancer, leuke ...
, diltiazem, expired
tetracycline Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including acne, cholera, brucellosis, plague, malaria, and syphilis. Common side effects in ...
,
highly active antiretroviral therapy The management of HIV/AIDS normally includes the use of multiple antiretroviral drugs as a strategy to control HIV infection. There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle. The use of multip ...
,
glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
,
tamoxifen Tamoxifen, sold under the brand name Nolvadex among others, is a selective estrogen receptor modulator used to prevent breast cancer in women and treat breast cancer in women and men. It is also being studied for other types of cancer. It has b ...
, environmental
hepatotoxin A hepatotoxin ('' Gr., hepato = liver'') is a toxic chemical substance that damages the liver. It can be a side-effect, but hepatotoxins are also found naturally, such as microcystins and pyrrolizidine alkaloids, or in laboratory environments, su ...
s (e.g.,
phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
, mushroom poisoning) ;Other:
celiac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barl ...
,
inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammation, inflammatory conditions of the colon (anatomy), colon and small intestine, Crohn's disease and ulcerative colitis being the principal types. Crohn's disease affects the small intestine a ...
,
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...
, hepatitis C (especially genotype 3), and alpha 1-antitrypsin deficiency


Pathology

Fatty change represents the intracytoplasmatic accumulation of triglycerides (neutral fats). At the beginning, the hepatocytes present small fat vacuoles (
liposomes A liposome is a small artificial vesicle, spherical in shape, having at least one lipid bilayer. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as drug deliver ...
) around the
nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...
(microvesicular fatty change). In this stage, liver cells are filled with multiple fat droplets that do not displace the centrally located nucleus. In the late stages, the size of the vacuoles increases, pushing the nucleus to the periphery of the cell, giving characteristic
signet ring A seal is a device for making an impression in wax, clay, paper, or some other medium, including an embossment on paper, and is also the impression thus made. The original purpose was to authenticate a document, or to prevent interference with a ...
appearance (macrovesicular fatty change). These vesicles are well-delineated and optically "empty" because fats dissolve during tissue processing. Large vacuoles may coalesce and produce fatty
cyst A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which ...
s, which are irreversible lesions. Macrovesicular
steatosis Steatosis, also called fatty change, is abnormal retention of fat (lipids) within a cell or organ. Steatosis most often affects the liver – the primary organ of lipid metabolism – where the condition is commonly referred to as fatty liver disea ...
is the most common form and is typically associated with alcohol, diabetes,
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
, and corticosteroids. Acute fatty liver of pregnancy and
Reye's syndrome Reye syndrome is a rapidly worsening encephalopathy, brain disease. Symptoms of Reye syndrome may include vomiting, personality changes, confusion, seizures, and loss of consciousness. While hepatotoxicity, liver toxicity typically occurs in the ...
are examples of severe liver disease caused by microvesicular fatty change. The diagnosis of steatosis is made when fat in the liver exceeds 5–10% by weight. Defects in fatty acid metabolism are responsible for
pathogenesis Pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Greek πάθος ''pat ...
of FLD, which may be due to imbalance in energy consumption and its combustion, resulting in lipid storage, or can be a consequence of peripheral resistance to insulin, whereby the transport of fatty acids from
adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
to the liver is increased. Impairment or inhibition of receptor molecules ( PPAR-α, PPAR-γ and SREBP1) that control the enzymes responsible for the oxidation and synthesis of fatty acids appears to contribute to fat accumulation. In addition, alcohol use disorder is known to damage mitochondria and other cellular structures, further impairing cellular energy mechanism. On the other hand, non-alcoholic FLD may begin as excess of unmetabolised energy in liver cells. Hepatic steatosis is considered reversible and to some extent nonprogressive if the underlying cause is reduced or removed. Severe fatty liver is sometimes accompanied by
inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
, a situation referred to as
steatohepatitis Steatohepatitis is a type of fatty liver disease, characterized by inflammation of the liver with concurrent fat accumulation in liver. Mere deposition of fat in the liver is termed steatosis, and together these constitute fatty liver changes. ...
. Progression to alcoholic steatohepatitis (ASH) or
non-alcoholic steatohepatitis Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. There are two types; non-alcoholic ...
(NASH) depends on the persistence or severity of the inciting cause.
Pathological Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...
lesions in both conditions are similar. However, the extent of inflammatory response varies widely and does not always correlate with degree of fat accumulation. Steatosis (retention of
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
) and onset of steatohepatitis may represent successive stages in FLD progression. Liver disease with extensive inflammation and a high degree of steatosis often progresses to more severe forms of the disease.
Hepatocyte A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein synthesis * Protein storage * Transformation of carbohydrates * Synthesis of cholesterol, ...
ballooning and
necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
of varying degrees are often present at this stage. Liver cell death and inflammatory responses lead to the activation of
hepatic stellate cell Hepatic stellate cells (HSC), also known as perisinusoidal cells or Ito cells (earlier ''lipocytes'' or ''fat-storing cells''), are pericytes found in the perisinusoidal space of the liver, also known as the space of Disse (a small area between th ...
s, which play a pivotal role in hepatic
fibrosis Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
. The extent of fibrosis varies widely. Perisinusoidal fibrosis is most common, especially in adults, and predominates in zone 3 around the terminal
hepatic veins In human anatomy, the hepatic veins are the veins that drain venous blood from the liver into the inferior vena cava (as opposed to the hepatic portal vein which conveys blood from the gastrointestinal organs to the liver). There are usually thre ...
. The progression to cirrhosis may be influenced by the amount of fat and degree of steatohepatitis and by a variety of other sensitizing factors. In alcoholic FLD, the transition to cirrhosis related to continued alcohol consumption is well-documented, but the process involved in non-alcoholic FLD is less clear.


Diagnosis

Most individuals are asymptomatic and are usually discovered incidentally because of abnormal liver function tests or hepatomegaly noted in unrelated medical conditions. Elevated liver enzymes are found in 50% of patients with simple steatosis. The serum
alanine transaminase Alanine transaminase (ALT) is a transaminase enzyme (). It is also called alanine aminotransferase (ALT or ALAT) and was formerly called serum glutamate-pyruvate transaminase or serum glutamic-pyruvic transaminase (SGPT) and was first characte ...
(ALT) level usually is greater than the
aspartate transaminase Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase (GOT, SGOT), is a pyridoxal phosphate (PLP)-dependent transaminase enzyme () that was first described by Arthur ...
(AST) level in the nonalcoholic variant and the opposite in alcoholic FLD (AST:ALT more than 2:1). Simple blood test may help to determine the magnitude of the disease by assessing the degree of liver fibrosis. For example, AST-to-platelets ratio index (APRI score) and several other score, calculated from the results of blood test, can detect the degree of liver fibrosis and predict the future formation of liver cancer. Imaging studies are often obtained during the evaluation process.
Ultrasonography Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...
reveals a "bright" liver with increased
echogenicity Echogenicity (misspelled sometimes as echogenecity) or echogeneity is the ability to bounce an echo, e.g. return the signal in ultrasound examinations. In other words, echogenicity is higher when the surface bouncing the sound echo reflects incre ...
.
Medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
can aid in diagnosis of fatty liver; fatty livers have lower
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
than
spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
s on computed tomography (CT), and fat appears bright in T1-weighted magnetic resonance images (MRIs). Magnetic resonance elastography, a variant of magnetic resonance imaging, is investigated as a non-invasive method to diagnose fibrosis progression.
Histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...
diagnosis by
liver biopsy Liver biopsy is the biopsy (removal of a small sample of tissue) from the liver. It is a medical test that is done to aid diagnosis of liver disease, to assess the severity of known liver disease, and to monitor the progress of treatment. Medica ...
is the most accurate measure of fibrosis and liver fat progression as of 2018. Conventional imaging methods, such as ultrasound, CT and MRI, are not specific enough to detect fatty liver disease unless fat occupies at least 30% of the liver volume.


Treatment

Decreasing caloric intake by at least 30% or by approximately 750–1,000 kcal/day results in improvement in hepatic steatosis. For people with
NAFLD Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. There are two types; non-alcoholic ...
or NASH, weight loss via a combination of diet and exercise was shown to improve or resolve the disease. In more serious cases, medications that decrease insulin resistance,
hyperlipidemia Hyperlipidemia is abnormally elevated levels of any or all lipids (fats, cholesterol, or triglycerides) or lipoproteins in the blood. citing: and The term ''hyperlipidemia'' refers to the laboratory finding itself and is also used as an umbre ...
, and those that induce weight loss such as bariatric surgery as well as Vitamin E have been shown to improve or resolve liver function.
Bariatric surgery Bariatric surgery (or weight loss surgery) includes a variety of procedures performed on people who are obese. Long term weight loss through the standard of care procedures ( Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversion ...
, while not recommended in 2017 as a treatment for fatty liver disease (FLD) alone, has been shown to revert FLD, NAFLD, NASH and advanced
steatohepatitis Steatohepatitis is a type of fatty liver disease, characterized by inflammation of the liver with concurrent fat accumulation in liver. Mere deposition of fat in the liver is termed steatosis, and together these constitute fatty liver changes. ...
in over 90% of people who have undergone this surgery for the treatment of
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
. In the case of long-term total parenteral nutrition induced fatty liver disease,
choline Choline is an essential nutrient for humans and many other animals. Choline occurs as a cation that forms various salts (X− in the depicted formula is an undefined counteranion). Humans are capable of some ''de novo synthesis'' of choline but r ...
has been shown to alleviate symptoms. This may be due to a deficiency in the methionine cycle.


Epidemiology

NAFLD affects about 30% of people in Western countries and 10% of people in Asia. In the United States rates are around 35% with about 7% having the severe form NASH. NAFLD affects about 10% of children in the United States. Recently the term Metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed to replace NAFLD. MAFLD is a more inclusionary diagnostic name as it is based on the detection of fatty liver by histology (biopsy),medical imaging or blood biomarkers but should be accompanied by either overweight/obesity, type 2 diabetes mellitus, or metabolic dysregulation. The new definition no longer excludes alcohol consumption or coexistence of other liver diseases such as viral hepatitis. Using this more inclusive definition, the global prevalence of MAFLD is an astonishingly high 50.7%. Indeed, also using the old NAFLD definition, the disease is observed in up to 80% of obese people, 35% of whom progress to NASH, and in up to 20% of normal weight people, despite no evidence of excessive alcohol consumption. FLD is the most common cause of abnormal
liver function test Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin ti ...
s in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. Fatty liver is more prevalent in Hispanic people than white, with black people having the lowest susceptibility. In the study of Children of the 90s, 2.5% born in 1991 and 1992 were found by ultrasound at the age of 18 to have non-alcoholic fatty liver disease; five years later transient elastography (fibroscan) found over 20% to have the fatty deposits on the liver, indicating non-alcoholic fatty liver disease; half of those were classified as severe. The scans also found that 2.4% had the liver scarring, which can lead to cirrhosis. After the lockdown of the COVID-19 pandemic, a study demonstrated that 48% of patients with liver steatosis gained weight, while 16% had a worsened steatosis grade. Weight gain was associated with poor adherence to the suggested diet, reduced levels of physical activity, and increased prevalence of PNPLA3 GG gene. PNPLA3 genes are already known risk factors for NAFLD.


In animals

Fatty liver disease can occur in pets such as reptiles (particularly
turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...
s) and birds as well as mammals like cats and dogs. The most common cause is
overnutrition Overnutrition (also known as hyperalimentation) is a form of malnutrition in which the intake of nutrients is oversupplied. The amount of nutrients exceeds the amount required for normal growth, development, and metabolism. The term can also ref ...
. A distinct sign in birds is a misshapen beak. Fatty livers can be induced via
gavage Force-feeding is the practice of feeding a human or animal against their will. The term ''gavage'' (, , ) refers to supplying a substance by means of a small plastic feeding tube passed through the nose ( nasogastric) or mouth (orogastric) into t ...
in geese or ducks to produce
foie gras Foie gras (, ; ) is a specialty food product made of the liver of a duck or goose. According to French law, foie gras is defined as the liver of a duck or goose fattened by gavage (force feeding). Foie gras is a popular and well-known delica ...
. Fatty liver can also be induced in ruminants such as sheep by a high caloric diet.


References


External links

* * Photo a
Atlas of Pathology

Healthdirect
{{DEFAULTSORT:Fatty Liver Diseases of liver Medical conditions related to obesity Histopathology Wikipedia medicine articles ready to translate no:Steatose pl:Alkoholowe stłuszczenie wątroby