Fatty liver is an abnormal accumulation of certain fats (triglycerides) inside liver cells.
- People with fatty liver may feel tired or have mild abdominal discomfort but otherwise have no symptoms.
- Sometimes fatty liver causes advanced liver disease such as fibrosis and cirrhosis.
- A liver biopsy may be needed to confirm the diagnosis and to determine the cause and extent of the damage.
- Doctors focus on controlling or eliminating the cause of fatty liver, such as metabolic syndrome or consumption of large amounts of alcohol.
(See also Overview of Liver Disease.)
The fatty liver may or may not be inflamed. Inflammation of the liver due to fatty liver is called steatohepatitis. This inflammation may develop into scarring (fibrosis). Fibrosis often progresses to cirrhosis (scarring that distorts the structure of the liver and impairs its function).
Fatty liver (with or without fibrosis) due to any condition except consumption of large amounts of alcohol is called nonalcoholic fatty liver disease (NAFLD). NAFLD develops most often in people with at least one of the components of metabolic syndrome:
- Excess body weight
- High fat levels in the blood (triglyceride and cholesterol)
- Insulin resistance
Inflammation of the liver due to NAFLD is called nonalcoholic steatohepatitis (NASH). This inflammation may develop into scarring (fibrosis) and cirrhosis.
Causes of Fatty Liver
The most common causes of fatty liver in the United States and other Western countries are
- Consumption of large amounts of alcohol
- Metabolic abnormalities, such as excess body weight, insulin resistance (as can occur in diabetes), and high levels of fats (triglycerides and cholesterol) in the blood
- Certain drugs, including corticosteroids, tamoxifen, and certain chemotherapy drugs
- Hereditary metabolic disorders
The combination of excess body weight, insulin resistance, and high triglyceride levels is called metabolic syndrome. All of these conditions cause fat to accumulate in liver cells by causing the body to synthesize more fat or by processing (metabolizing) and excreting fat more slowly. As a result, fat accumulates and is then stored inside liver cells. Just consuming a high-fat diet does not result in fatty liver.
Rarely, fat accumulates in the liver during late pregnancy. This disorder, called fatty liver of pregnancy or microvesicular steatosis, is usually considered a different disorder from fatty liver.
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Symptoms of Fatty Liver
Fatty liver usually causes no symptoms. Some people feel tired or have vague abdominal discomfort. The liver tends to enlarge and can be detected by doctors during a physical examination.
Diagnosis of Fatty Liver
- Blood tests
- Imaging tests, such as ultrasonography
- Sometimes a liver biopsy
If doctors suspect fatty liver, they ask about alcohol use. This information is crucial. Continued and excessive alcohol use can cause severe liver damage.
Blood tests to detect liver abnormalities, such as inflammation, are important because inflammation may lead to cirrhosis. Additional blood tests help exclude other causes of liver abnormalities, such as viral hepatitis. Ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) of the abdomen can detect excess fat in the liver but cannot always determine whether inflammation or fibrosis is present (see Imaging Tests of the Liver and Gallbladder). Additionally, new imaging tests such as magnetic resonance elastography (MRE) or ultrasound elastrography can determine if scar tissue or cirrhosis is present. However, in obese people, the fibrosis score can sometimes be falsely elevated due to high fat content, and people may need a liver biopsy.
Liver biopsy is the most accurate test and may be necessary to confirm the diagnosis. For the biopsy, a doctor gives a local anesthetic to lessen any pain, then inserts a long hollow needle through the skin and into the liver to obtain a small piece of liver tissue for examination under a microscope. The biopsy can help determine whether fatty liver is present, whether it resulted from alcohol or certain other specific causes, and how severe the liver damage is.
Prognosis of Fatty Liver
Excess fat in the liver by itself is not necessarily a serious problem. For example, if alcohol is the cause, the fat can disappear, usually within 6 weeks, when people stop drinking. However, if the cause is not identified and corrected, fatty liver can have serious consequences. For example, if people continue to drink large amounts of alcohol or if a drug causing fatty liver is not stopped, repeated liver injury may eventually lead to cirrhosis.
Women with fatty liver of pregnancy have a worse prognosis.
Treatment of Fatty Liver
- Control or elimination of the cause
Treatment of fatty liver focuses on controlling or eliminating the cause of fatty liver. For example, people should
- Stop taking any drug that could be causing fatty liver
- Lose weight
- Take measures to control diabetes or lower triglyceride levels
- Stop drinking alcohol
A decrease in body weight of 5% can decrease fat content in the liver, a 7% decrease can reduce inflammation and nonalcoholic steatohepatitis, and a 10% decrease can help reverse scarring and fibrosis.
Doctors sometimes try giving vitamin E and thiazolidinediones (a class of drugs, including rosiglitazone and pioglitazone, that are used to treat diabetes) to treat fatty liver that is not caused by alcohol. However, specialists are using these drugs less often because they often cause adverse effects and may not make a difference in the long-term. New drug treatments are being developed in clinical trials. Doctors can refer people to a liver specialist (hepatologist) to discuss whether they would be a good candidate for these new drugs.
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