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Nonalcoholic Steatohepatitis:

What is nonalcoholic steatohepatitis?

Nonalcoholic steatohepatitis (NASH) is a common, often "silent" liver disease.  It resembles alcoholic liver disease, but occurs in people who drink little or no alcohol.  The primary concern with patients who have NASH is fat in the liver, along with inflammation and damage of the liver.  Most people with NASH do not have symptoms and are not aware that they have a liver problem. Nevertheless, NASH can be severe and can lead to cirrhosis, in which the liver is permanently damaged and scarred and no longer able to work properly. 

NASH affects approximately 2 to 5 percent of Americans.  An additional 10 to 20 percent of Americans have fat in their liver, but do not have inflammation or liver damage, a condition called "fatty liver."  Although having fat in the liver is not normal, by itself it probably causes little harm or permanent damage.  If fat is suspected based on blood test results or scans of the liver, this problem is called nonalcoholic fatty liver disease (NAFLD). If a liver biopsy is performed in this case, it will show that some people have NASH while others have simple fatty liver.

Both NASH and NAFLD are becoming more common, possibly because of the greater number of Americans with obesity.  In the past 10 years, the rate of obesity has doubled in adults and tripled amongst the population of children.  Obesity also contributes to diabetes and high blood cholesterol, which can further complicate the health of someone with NASH.  Diabetes and high blood cholesterol are also becoming more common among Americans.

Symptoms of nonalcoholic steatohepatitis:

NASH is usually a silent disease with few or no symptoms. Patients generally feel well in the early stages and only begin to have symptoms—such as fatigue, weight loss, and weakness—once the disease is more advanced or cirrhosis develops. The progression of NASH can take years, even decades. The process can stop and, in some cases, reverse on its own without specific therapy. Or NASH can slowly worsen, causing scarring or "fibrosis" to appear and accumulate in the liver. As fibrosis worsens, cirrhosis develops; the liver becomes seriously scarred, hardened, and unable to function normally. Not every person with NASH develops cirrhosis, but once serious scarring or cirrhosis is present, few treatments can halt the progression. A person with cirrhosis experiences fluid retention, muscle wasting, bleeding from the intestines, and liver failure. Liver transplantation is the only treatment for advanced cirrhosis with liver failure, and transplantation is increasingly performed in people with NASH. NASH ranks as one of the major causes of cirrhosis in America, behind hepatitis C and alcoholic liver disease.

Causes of nonalcoholic steatohepatitis:

Although NASH has become more common, its underlying cause is still unclear.  NASH most often occurs in persons who are middle-aged and overweight or obese.  Many patients with NASH have elevated blood lipids, such as cholesterol and triglycerides, and many have diabetes or pre-diabetes; however, not every obese person or every patient with diabetes has NASH.  Some patients with NASH are not obese, do not have diabetes, and have normal blood cholesterol and lipids.  NASH can occur without any apparent risk factor and can even occur in children.  Therefore, NASH is not simply obesity that affects the liver.  While the underlying reason for the liver injury that causes NASH is not known, several factors are possible causes of NASH:

Treatment & Prevention options:

Currently, there are no specific therapies for NASH.  The most important recommendations given to persons with this disease include:

These are standard recommendations, but they can make a difference. They are also helpful for other conditions, such as heart disease, diabetes, and high cholesterol.  A major attempt should be made to lower body weight into the healthy range.  Weight loss can improve liver tests in patients with NASH and may reverse the disease to some extent.  Research at present is focusing on how much weight loss improves the liver in patients with NASH and whether this improvement lasts over a period of time.

Related information:

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Last Revised: 09/07/2006