Nonalcoholic steatohepatitis (NASH) is a common liver disease. The term NASH was coined in 1980 to describe 20 nonalcoholic patients with liver biopsy changes compatible with alcoholic hepatitis. Because this condition is becoming more widely recognized, Kumar and Malet prepared a concise review outlining key points of this disease for clinicians.

The true prevalence of NASH is unknown but has been reported in up to 9 percent of patients undergoing liver biopsy. NASH has been described most frequently in obese women who are diabetic or hyperlipidemic. Type 2 diabetes (formerly known as non–insulin-dependent diabetes) has been reported in up to 75 percent of patients with NASH. Histologic changes in the liver are characterized by fatty changes and hepatocyte injury, with or without fibrosis. Changes of cirrhosis may be found. Most patients with NASH are asymptomatic, although some report fatigue, malaise or right upper quadrant discomfort. There are no reliable distinguishing laboratory features. Generally, modest elevations of aminotransferase levels are noted, in the two-to threefold range.

Liver biopsy remains the gold standard for diagnosis. Although NASH generally takes an indolent course, a substantial proportion of patients develop fibrosis that leads to cirrhosis and complications from portal hypertension. There are no reliable criteria that can be used to identify patients at higher risk of progression.

Weight loss has been shown to result in biochemical and histologic improvement in patients with NASH and remains the mainstay of treatment. A reasonable strategy is to restrict all alcohol intake. Good glycemic control of diabetes, as well as treatment of hyperlipidemia, while not determined to affect the course, also seem reasonable.

NASH should be considered in the differential diagnosis of patients with persistently elevated liver enzyme levels, particularly in obese patients with diabetes and hyperlipidemia. The course of this disease is highly variable, but it may proceed to cirrhosis. Although no proven therapy exists, weight loss may have a beneficial effect.