Fatty liver disease

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Fatty liver
Other names	Hepatic steatosis
Micrograph showing a fatty liver (macrovesicular steatosis), as seen in non-alcoholic fatty liver disease. Trichrome stain.
Specialty	Gastroenterology
Symptoms	None, tiredness, pain in the upper right side of the abdomen[1][2]
Complications	Cirrhosis, liver cancer, esophageal varices[1][3]
Types	Non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease[1]
Causes	Alcohol, diabetes, obesity[3][1]
Diagnostic method	Based on the medical history supported by blood tests, medical imaging, liver biopsy[1]
Differential diagnosis	Viral hepatitis, Wilson disease, primary sclerosing cholangitis[3]
Treatment	Avoiding alcohol, weight loss[3][1]
Prognosis	Good if treated early[3]
Frequency	NAFLD: 30% (Western countries)[2] ALD: >90% of heavy drinkers[4]

Fatty liver disease (FLD), also known as hepatic steatosis and steatotic liver disease (SLD), is a condition where excess fat builds up in the liver.^[1] Often there are no or few symptoms.^[1][2] Occasionally there may be tiredness or pain in the upper right side of the abdomen.^[1] Complications may include cirrhosis, liver cancer, and esophageal varices.^[1][3]

The main subtypes of fatty liver disease are metabolic dysfunction–associated steatotic liver disease (MASLD, formerly "non-alcoholic fatty liver disease" (NAFLD)) and alcohol-associated liver disease (ALD), with the category "metabolic and alcohol associated liver disease" (metALD) describing an overlap of the two.^[5]

The primary risks include alcohol, type 2 diabetes, and obesity.^[1][3] Other risk factors include certain medications such as glucocorticoids, and hepatitis C.^[1] It is unclear why some people with NAFLD develop simple fatty liver and others develop nonalcoholic steatohepatitis (NASH), which is associated with poorer outcomes.^[1] Diagnosis is based on the medical history supported by blood tests, medical imaging, and occasionally liver biopsy.^[1]

Treatment of NAFLD is generally by dietary changes and exercise to bring about weight loss.^[1] In those who are severely affected, liver transplantation may be an option.^[1] More than 90% of heavy drinkers develop fatty liver while about 25% develop the more severe alcoholic hepatitis.^[4] NAFLD affects about 30% of people in Western countries and 10% of people in Asia.^[2] NAFLD affects about 10% of children in the United States.^[1] It occurs more often in older people and males.^[3][6]