Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease, or NAFLD, refers to the buildup of excess fat in the liver.

Some fat in the liver is normal, but when fat composes 5 to 10 percent of the liver's total weight, it is known as a fatty liver. NAFLD is the most common liver disease in the U.S., affecting up to 25 percent of the population.

The causes of NAFLD are unknown, but are likely to involve many factors ranging from genetic characteristics to personal lifestyle. It commonly relates to obesity, insulin resistance and a sedentary lifestyle, and is often associated with metabolic syndrome. Patients may have elevated blood lipids, diabetes or are pre-diabetes.

Some risk factors may increase the chance of developing NAFLD, while other protective factors may decrease the chance of developing NAFLD. The factors that determine whether a patient progresses from NAFLD to more severe liver disease are also unknown.

The time it takes for a patient to progress to more severe disease is also uncertain. Several factors are possible candidates for the underlying reasons for liver injury, including:

  • Insulin resistance
  • Release of toxic inflammatory proteins by fat cells
  • Oxidative stress inside liver cells

End-stage NAFLD accounts for 4 percent to 10 percent of all liver transplants.

Symptoms of NASH

NASH is usually a disease with few or no symptoms. Patients with NASH usually will have fat, inflammation and damage in the liver. Since NASH is a “silent” liver disease, most patients feel well and are usually unaware of their condition.

When the disease is more advanced or cirrhosis develops, patients may experience symptoms such as fatigue, weight loss, and weakness.

Once the liver is cirrhotic, few treatments can prevent the progression. A cirrhotic patient may experience fluid retention, bleeding from the intestines, muscle wasting and liver failure. Currently, liver transplantation is the only treatment for advanced cirrhosis with liver failure.See Liver Disease Care

Nonalcoholic Steatohepatitis (NASH)

Nonalcoholic steatohepatitis, or NASH, can result from NAFLD. NASH refers to a disease that causes inflammation and scarring in the liver. Over time, this can result in permanent hardening of the liver tissues, the last stage of liver disease known as cirrhosis. At the point that cirrhosis develops, your liver will have difficulty performing its normal functions, which can cause serious illness and even death. 

While it resembles alcoholic liver disease, NASH occurs in people who drink little to no alcohol.

NASH is usually first suspected by observing elevations in liver enzymes such as alanine aminotransferase (ALT) or aspartate aminotransferase (AST). Until recently, the only way to prove a diagnosis of NASH was through a liver biopsy (small amount of liver tissue removed by needle). The biopsy results may show different amounts of fat, inflammation (swelling), and scarring in the liver. NASH can lead to severe liver disease in some patients.

As an alternative to biopsy, we now participate in a program that will help determine biomarkers for NASH. Biomarkers are molecules that indicate normal or abnormal processes taking place in your body that could indicate an underlying condition or disease.

The Non-Invasive Biomarkers of Metabolic Liver Disease (NIMBLE) project will directly compare imaging and blood-based biomarkers to biopsy results to define the best tools for diagnosing NASH. This information will help physicians identify patients who are most likely to progress to serious complications, such as liver failure or cancer.

A Leader in NAFLD Research

Our liver disease team includes Rohit Loomba, MD, a leading expert in clinical research for nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). He serves on the national board of directors for the American Liver Foundation and works in close collaboration with the National Institutes of Health (NIH).

Dr. Loomba is the founding director of the UC San Diego NAFLD Translational Research. His team conducts leading-edge research in all aspects of NAFLD including, genetics, noninvasive biomarkers and epidemiology. Their efforts are helping shape new therapies for the treatment of NASH and NASH-related fibrosis. His research is funded by the NIH, American Gastroenterology Association and National Science Foundation.

Currently we have several drug trials and observational studies mainly related to Nonalcoholic Fatty Liver Disease (NAFLD) and pharmaceutical trials for patients with NAFLD, nonalcoholic steatohepatitis (NASH), and NASH cirrhosis. For information, call 858-246-2179.

Classes & Support Groups

Education classes and support groups for people who have hepatitis C and liver cancer are available. Learn more about liver transplant resources.

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