What is the definition of Nonalcoholic Steatohepatitis?
Nonalcoholic steatohepatitis, or NASH, is a common, often “silent” liver disease. It resembles alcoholic liver disease, but occurs in people who drink little or no alcohol. The major feature in NASH is fat in the liver, along with inflammation and damage. Most people with NASH feel well 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 most often occurs in people who are middle aged and overweight or obese. Affected individuals may also have elevated levels of blood lipids (such as cholesterol and triglycerides) and many have diabetes or prediabetes. Treatment is centered around working towards a healthy lifestyle, including weight reduction, dietary modification, increased activity and avoidance of alcohol and unnecessary medications. The underlying cause of NASH remains unclear.
What are the alternative names for Nonalcoholic Steatohepatitis?
- Non-alcoholic steatohepatitis
- Non-alcoholic fatty liver disease
What are the causes for Nonalcoholic Steatohepatitis?
The underlying cause of NASH remains unclear. It 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 prediabetes. However, not every obese person or every patient with diabetes has NASH. Furthermore, 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.
While the underlying reason for the liver injury that causes NASH is not known, several factors are possible candidates:
- insulin resistance
- release of toxic inflammatory proteins by fat cells (cytokines)
- oxidative stress (deterioration of cells) inside liver cells
What are the current treatments for Nonalcoholic Steatohepatitis?
Currently, there are no specific therapies for NASH. The most important recommendations given to persons with this disease are to:
- reduce their weight (if obese or overweight)
- follow a balanced and healthy diet
- increase physical activity
- avoid alcohol
- avoid unnecessary medications
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.
Individuals with other medical conditions (diabetes, high blood pressure, or elevated cholesterol) should be treated with medication as advised by their physician.
Some new treatment options are now being studied in clinical trials. These include the use of antioxidants (such as vitamin E, selenium, and betaine) and some newer antidiabetic medications (metformin, rosiglitazone, and pioglitazone) which treat insulin resistance.
How is Nonalcoholic Steatohepatitis diagnosed?
NASH is usually first suspected when elevations are noted in liver tests that are included in routine blood test panels. These may include alanine aminotransferase (ALT) or aspartate aminotransferase (AST). When further evaluation shows no apparent reason for liver disease (such as medications, viral hepatitis, or excessive use of alcohol) and when x-rays or imaging studies of the liver show fat, NASH is suspected. The only way to definitely diagnosis NASH and separate it from simple fatty liver is through a liver biopsy. For a liver biopsy, a needle is inserted through the skin to remove a small piece of the liver. NASH is diagnosed when examination of the tissue with a microscope shows fat along with inflammation and damage to liver cells. If the tissue shows fat without inflammation and damage, simple fatty liver or NAFLD is diagnosed. An important piece of information learned from the biopsy is whether scar tissue has developed in the liver. Blood tests and scans cannot reliably provide this information at this time.