Non-Alcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), also known as steatohepatitis, is an inflammation of the liver caused by an accumulation of fat deposits in the liver tissue. In most people, the underlying problem is obesity, diabetes or both. Additional factors are a family history of diabetes and high blood lipids in people who are not obese. In some patients, genetic factors appear to be important.

NAFLD typically shows up as an unexpected abnormality in liver function tests, usually the alanine aminotransferase (ALT) test, in people who otherwise feel well. The elevation of this test generally is minor and in younger patients, does not indicate a serious liver condition. However, if the cause of NAFLD, such as obesity or diabetes, is not treated, the condition may progress.

In people over the age of 50, the first indication of NAFLD may be a sign of serious liver disease, cirrhosis. Studies are underway to determine the precise risk of progression of NAFLD to cirrhosis; at this time, it is estimated as 20 percent.

As the prevalence of obesity has been increasing in the United States, the incidence of NAFLD also has been increasing. As a result, NAFLD is now among the most common reasons that patients are referred for liver transplantation. The UCSF Liver Transplant Program, which integrates the efforts of gastroenterologists and surgeons, performs over 100 transplants each year, making it one of the leading programs in the U.S. Survival statistics are among the very best in the country.

The signs and symptoms of nonalcoholic fatty liver disease (NAFLD) vary widely, depending on the stage of the condition. During the early or middle stages of the disease, patients typically have no symptoms directly related to liver disease. However, as the disease advances, patients may experience symptoms of cirrhosis, including:

  • Fatigue
  • Memory loss or confusion
  • Fluid retention in the abdomen or legs
  • Passage of tarry black stools, which suggests internal bleeding

Nonalcoholic fatty liver disease (NAFLD) often is found incidentally, as part of testing for an unrelated problem. The following tests may be used to confirm the diagnosis:

  • Blood Tests — Blood tests that measure global liver function and indicate inflammatory activity will be performed, along with additional blood tests to exclude viral hepatitis.
  • Liver Ultrasound — This is a simple imaging procedure that looks for irregularities in the shape and consistency of the liver and for problems of the biliary tract, such as gallstones.
  • Computed Tomography (CT) — Computed tomography (CT) is a method of body imaging in which a thin X-ray beam rotates around the patient, to provide a detailed view of the liver.
  • Liver Biopsy — In some cases, a liver biopsy may be needed to make a definite diagnosis of NAFLD. The test also helps in defining the stage of disease and severity of liver inflammation. During the biopsy, which is an outpatient procedure and performed under local anesthesia, a needle is inserted into the liver to obtain a small sample.

Currently, the goal of treatment for NAFLD patients who are obese and/or have elevated blood lipids (fat) is weight loss. Those who are diabetic with poor control of blood sugar should work with a diabetes specialist and dietitian to control their blood sugar. All patients with NAFLD should avoid alcohol.

The treatment for NAFLD is evolving and rigorously being investigated in various research studies. UCSF is participating in one of the larger trials investigating NAFLD and new therapies for the condition.

Liver Transplantation

In some cases, NAFLD may progress to liver failure and require liver transplantation. The evaluation for a transplant is complex and generally requires several months. Therefore, even patients who are feeling well should be referred for a transplant at the first sign of liver failure or if they have advanced liver disease diagnosed by X-ray studies or liver biopsy.

UCSF Research & Clinical Trials


Reviewed by health care specialists at UCSF Medical Center.

Related Information

UCSF Clinics & Centers


Liver Transplant Program
400 Parnassus Ave., Third Floor
San Francisco, CA 94143
Phone: (415) 353-1888
Fax: (415) 353-8917
Appointment information

Liver Disease and Liver Transplant
350 Parnassus Ave., Suite 300
San Francisco, CA 94143
Phone: (415) 353-2318
Fax: (415) 353-2407
Appointment information