Nonalcoholic steatohepatitis (NASH)
Nonalcoholic steatohepatitis (NASH) is a liver condition characterized by the accumulation of excess fat in the liver, leading to inflammation that is not caused by alcohol consumption. It is often associated with conditions such as obesity, diabetes, metabolic syndrome, high blood pressure, and hyperlipidemia. Many individuals with NASH experience no symptoms, while those who do may notice fatigue or mild abdominal discomfort. The disease can progress to more severe liver conditions, including cirrhosis, which is marked by extensive liver scarring and loss of function.
Diagnosis typically involves liver function tests, and a definitive diagnosis is made through a liver biopsy. Treatment primarily focuses on managing associated health conditions and promoting a healthy lifestyle, including weight loss and regular exercise. Some studies suggest that dietary changes and specific vitamin supplementation may also help improve liver health. As the prevalence of NASH rises, particularly in the context of increasing obesity rates, ongoing research aims to better understand the disease and explore effective treatment options.
Nonalcoholic steatohepatitis (NASH)
ALSO KNOWN AS:Nonalcoholic fatty liver disease (NAFLD)
ANATOMY OR SYSTEM AFFECTED: Endocrine system, gastrointestinal system, liver
DEFINITION: Fatty inflammation of the liver that is not caused by alcohol
CAUSES: Accumulation of fat in the liver; related to diabetes, metabolic syndrome, high blood pressure, hyperlipidemia
SYMPTOMS: Often none, sometimes fatigue or mild abdominal discomfort; enlarged liver and severe liver disease may develop
DURATION: Chronic
TREATMENTS: Often none; treatment of associated conditions, liver transplantation if severe
Causes and Symptoms
The liver is a complex organ located in the right upper abdomen. It plays a role in converting carbohydrates, fats, and proteins from food into forms that the body can use. It also manufactures cholesterol, stores sugar, and metabolizes certain medications and chemicals.
Nonalcoholic steatohepatitis (NASH), also called fatty liver disease, is characterized by the storage of excess fat in the liver, with associated inflammation. The cause of this disorder is not completely understood. The accumulation of excess fat in the liver is related to the body’s inability to use its own insulin, a common problem found in adults and children with central obesity. NASH is also found in individuals with other medical conditions, such as diabetes, metabolic syndrome, high blood pressure, and hyperlipidemia. Other causes of excess fat storage include certain medications, exposure to occupational toxins, and some surgical procedures. The excess fat causes damage to liver cells similar to the damage caused by excess alcohol intake.
The majority of people with NASH have no symptoms, in which case the disorder is suspected only from liver-function tests. Studies have shown, however, that elevated liver enzymes do not always occur in individuals with NASH. If symptoms are present, they may include fatigue or mild discomfort in the upper right side of the abdomen. The liver may be enlarged. Fatty liver may be identified on ultrasound, but a biopsy of the liver must be performed in order to determine the extent of the disorder. A liver biopsy is a minor surgical procedure that is performed by inserting a needle into the liver through a small incision and removing cells for evaluation under the microscope. The severity of the disorder may range from inflammation of the liver to cirrhosis, a chronic, progressive disease with extensive scarring of the liver that causes destruction of liver cells. If the destruction advances, then the liver loses the ability to function. Severe liver disease occurs in approximately 20 percent of those with NASH.
Treatment and Therapy
Treatment goals include the identification and treatment of associated conditions and the reduction of insulin resistance. Adopting a healthy lifestyle is the primary treatment for NASH. Those who are overweight are encouraged to lose weight gradually and to exercise. Triglyceride and cholesterol levels should be kept within normal limits. Strict blood-sugar control is indicated for diabetics with NASH. A few studies have found that daily vitamin E reduces abnormal liver enzymes. Insulin-sensitizing drugs, normally used by diabetics, have also shown promise for the treatment of NASH and its associated insulin resistance. Lipid-lowering drug studies have also shown some improvement in blood liver function tests, but not in the follow-up biopsy tests for inflammation and damage.
It is generally recommended that individuals with NASH avoid alcohol and certain medications, such as acetaminophen, that may further damage the liver. If the individual develops severe cirrhosis, then a liver transplant may be necessary to avoid death.
Perspective and Prospects
In 1958, fatty liver disease was first identified in a small group of obese individuals. In 1980, the term "nonalcoholic steatohepatitis" was coined to describe a small group of patients at the Mayo Clinic who had liver biopsy findings similar to those with alcoholic liver disease. Since 2000, pediatricians have reported the presence of NASH in obese children, as well as in children with other endocrine disorders. The increase in obesity and diabetes in the United States has been linked to the increasing numbers of individuals diagnosed with NASH.
Diagnosis is confirmed with a liver biopsy or, less commonly, with a noninvasive diagnostic method. Ultrasound and abdominal computed tomography (CT) scans are sometimes used, as are newer x-ray techniques and laboratory blood analyses.
Drug therapy continues to be investigated after promising pilot studies. Further study is also needed in the area of the disease process and its potential for progression in some individuals.
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