You don't have to be a heavy drinker to suffer from liver problems. Nonalcoholic fatty liver disease has become the most common chronic liver disease in all developed countries, including the United States, says Dr. Srinevas K. Reddy, assistant professor of surgery at the University of Maryland School of Medicine and a liver surgeon at the University of Maryland Medical Center.
The disease is associated with overeating rather than drinking too much alcohol. The number of people with nonalcoholic fatty liver disease is steadily increasing and is on pace to become the most common cause of primary liver cancer and liver transplantation by 2025, Reddy says.
What is nonalcoholic fatty liver disease?
Nonalcoholic fatty liver disease is a condition where more than 5 percent of liver cells contain abnormally high concentrations of fat. Nonalcoholic fatty liver disease is broadly categorized into two types, "simple" steatosis (without inflammation) and nonalcoholic steatohepatitis, or fatty liver with inflammation. The majority of patients with nonalcoholic fatty liver disease have simple steatosis. Nonalcoholic steatohepatitis is the more serious form of fatty liver disease that may lead to cirrhosis, primary liver cancer and dysfunction in other organs.
Who is most likely to get nonalcoholic fatty liver disease?
The most prominent risk factors for nonalcoholic fatty liver disease are components of the metabolic syndrome, including diabetes mellitus, high blood pressure, high blood-cholesterol levels and obesity. Up to 90 percent of patients with morbid obesity and at least 50 percent of those with type II diabetes mellitus will have nonalcoholic fatty liver disease. Because of the obesity epidemic, the prevalence of nonalcoholic fatty liver disease is estimated at 25 percent to 40 percent of the U.S. population.
Traditionally, chronic liver disease was thought of as mostly an adult male disorder owing to the male predominance of hepatitis C and/or alcoholic liver disease. However, nonalcoholic fatty liver disease occurs in nearly every segment of the population, including women, children and the elderly. Hence, liver disease in general is becoming a more important health care problem across the United States. While every ethnic group is affected, nonalcoholic fatty liver disease is most prevalent in Hispanics.
What are the symptoms of nonalcoholic fatty liver disease?
Since the liver is such a resilient organ, most patients with nonalcoholic fatty liver disease do not have symptoms or any laboratory abnormalities. Right upper abdominal pain is the most common symptom that does occur among patients with nonalcoholic fatty liver disease. If nonalcoholic fatty liver disease progresses to cirrhosis, patients may develop jaundice, ascites (increased fluid in the abdomen) and increased abdominal girth. The most common cause of elevated liver enzymes as an incidental finding on laboratory studies is nonalcoholic steatohepatitis.
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The most effective treatments for nonalcoholic fatty liver disease include weight loss and exercise. These treatments also improve the conditions associated with nonalcoholic fatty liver disease, such as diabetes mellitus, high blood pressure and elevated blood-cholesterol levels. In addition to changes in diet and increased exercise, weight loss surgery has also been shown to reverse the effects of nonalcoholic fatty liver disease. Fatty inflammation, also known as nonalcoholic steatohepatitis, can also be treated with vitamin E and thiaglitazones, a group of medicines also used to treat diabetes mellitus.
What can happen if someone isn't treated for nonalcoholic fatty liver disease?
In patients with nonalcoholic steatohepatitis, the fatty inflammation can lead to cirrhosis and primary liver cancer. Recent evidence also suggests that nonalcoholic fatty liver disease is an indicator and/or a key regulator of deleterious effects of the metabolic syndrome on cardiovascular and cerebrovascular disease. Thus, nonalcoholic fatty liver disease may increase the risk of heart attack and/or stroke. Finally, emerging evidence suggests that nonalcoholic fatty liver disease may be related to abnormalities in gut function and bacterial balance. Hence, fatty liver disease may also be related to inflammatory bowel disease, diverticulitis and gallstone related disorders.