Nonalcoholic Steatohepatitis (NASH) is the term used to describe the distinct clinical entity in which patients lack a history of significant alcohol consumption but have liver biopsy findings indistinguishable from alcoholic hepatitis Other terms that have infrequently been used to describe this condition include pseudoalcoholic hepatitis, alcohol-like hepatitis, fatty liver hepatitis, steatonecrosis, and diabetic hepatitis.
DEFINITION.
1.A liver biopsy showing moderate to gross macrovesicular fatty change with inflammation (lobular or portal) and with or without Mallory bodies, fibrosis, or cirrhosis. As noted above, these changes are indistinguishable from those of alcoholic hepatitis.
2.Convincing evidence of negligible alcohol consumption (less than 40 g of ethanol per week).
3Absence of serologic evidence of infection with hepatitis B or hepatitis C .
Nonalcoholic steatohepatitis (NASH) is a liver disease that, until recently, has been underrecognized as a common cause of elevated liver enzymes. This distinct clinical entity is characterized by liver biopsy findings similar to those seen in alcoholic hepatitis but in the absence of alcohol consumption sufficient to cause such changes. Patients with NASH are often middle-aged and obese, with coexisting diabetes or hyperlipidemia, but NASH also occurs in younger lean, otherwise healthy individuals and even in children. Although NASH is generally a benign disorder, it may be progressive, leading to cirrhosis and complications of portal hypertension. Liver biopsy remains the gold standard for diagnosis. Therapy for NASH remains poorly defined, although weight reduction and ursodeoxycholic acid may have a beneficial effect.

What is the risk of NASH?

In NASH, which resembles alcoholic steatohepatitis, the inflammation of the liver is associated with an increase of fat deposits and typically occurs in middle-aged, overweight, and often diabetic patients who do not drink alcohol. It has also been connected with rapid weight loss, or in women taking hormones (estrogen). The fatty tissue in the liver may break up liver cells (steatonecrosis) and the patient may develop cirrhosis (scarring of the liver). Recent studies indicate that NASH can result in the development of fibrous tissue in the liver (fibrosis) in up to 40% of patients or cirrhosis in 5-10% of patients. It is not certain why some NASH patients will progress to this serious form of chronic liver disease while others do not. Studies report that the progression to fibrosis or cirrhosis for NASH patients is variable but can occasionally occur in less that 20 years. Some studies have shown that 20% to 40% of people who are grossly overweight will develop NASH. If a patient is grossly overweight, however, it does not mean that he/she will develop NASH. Many patients with NASH will show an increase of certain iron proteins (ferritin) in their blood, but whether this relates to any injury to the liver is unknown.

Despite the frequency of histologic progression and the histologic similarity between NASH and alcoholic hepatitis, the outcome is quite different in the two disorders. Approximately 38 to 50 percent of patients with alcoholic hepatitis progress to cirrhosis over a seven-year period; comparable values for NASH are much lower at 8 to 26 percent. NASH is also associated with higher 5- and 10-year survival rates than alcoholic hepatitis (67 versus 38 percent and 59 versus 15 percent, respectively).

 

How is NASH diagnosed?

Many NASH patients are unaware of their conditions because they do not exhibit any symptoms. In most cases, NASH causes a slight increase during liver enzyme tests, as do other forms of liver disease. AS with fatty liver, the physician will first eliminate the other possible causes of chronic liver disease. Images of the liver are obtained by an ultrasound test, a CT scan, or an MRI scan. The diagnosis must be confirmed by liver biopsy.

How is NASH treated?

Presently, there is no specific treatment for NASH that is universally agreed upon. However, patients who are obese, diabetic, and have high lipids (fats) in their blood are advised to lose weight and control their diabetes and elevated lipids. Usually, a low fat, low calorie diet is recommended along with insulin or medications to lower blood sugar for diabetes. For many patients with NASH whow are not overweight and not diabetic, a low fat diet is recommended. Patients with NASH should avoid alcohol or other substances that could be harmful to the liver. More research is needed to understand what causes NASH so that more effective therapies can be developed.