Increased levels of liver transaminase in patients are commonly noted by family physicians. While many cases can be explained by previously undetected alcohol use, infectious hepatitis, or use of hepatotoxic medications, a large percentage have no obvious cause. Fatty liver is increasingly recognized as a common etiology of these otherwise unexplained cases of increased transaminase levels. Angulo reviewed recent progress in the understanding of nonalcoholic fatty liver disease.

Its widespread prevalence and occasional progression to end-stage cirrhosis are the chief reasons that nonalcoholic fatty liver disease is receiving increased clinical attention. More than two thirds of all obese persons have fatty liver, and 90 percent of persons weighing more than twice their ideal body weight are affected. Diabetes and hyperlipidemia (especially hypertriglyceridemia) increase the risk of developing nonalcoholic fatty liver disease. Although the typical patient with nonalcoholic fatty liver disease is a middle-aged obese woman, the disease also affects nonobese persons, including children with type 1 diabetes mellitus.

Most patients are asymptomatic, and hepatomegaly is the only common finding on physical examination. In patients with advanced disease, the typical findings of cirrhosis become apparent. Ultrasonography of the liver has good sensitivity and specificity for detecting fatty infiltration of the liver, as does computed tomography. These modes are not helpful, however, in determining the severity of the disease. Liver biopsy is a more definitive way to grade the severity of fatty liver disease. Histologic examination of biopsy specimens allows for grading of fatty infiltration and resultant hepatitis and fibrosis.

Most patients with nonalcoholic fatty liver disease do not progress to advanced fibrosis and cirrhosis. Risk factors for advanced disease have become clearer (e.g., type 2 diabetes mellitus, age 45 years or more, body mass index of 30 or more, and aspartate aminotransferase: alanine aminotransferase ratio more than 1).

Treatment options are still limited for patients at higher risk of progressive disease. While weight loss can lead to normalization of liver test results and a decrease in fatty infiltration, it does not always improve the amount of inflammation or fibrosis. Rapid weight loss has even worsened fatty liver disease in some cases. In small pilot studies, medications such as gemfibrozil, vitamin E, and metformin have been shown to improve liver test parameters, but the author notes that these results need to be confirmed in larger, controlled studies. Gradual weight loss and good control of hyperglycemia and hyperlipidemia are recommended. Liver transplantation has been necessary in patients with end-stage cirrhosis, but fatty liver disease may recur in the transplanted organ in some patients.