Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) occurs when fat is deposited into hepatocytes without a known cause (such as with alcoholic fatty liver disease). The deposition of fat may lead to hepatic inflammation (hepatitis) and may eventually lead to cirrhosis.


"Non-alcoholic fatty liver disease" (NAFLD) is differentiated by some into:

  • non-alcoholic fatty liver (NAFL)
    • signs of hepatic inflammation are absent
  • non-alcoholic steatohepatitis (NASH)
    • signs of hepatic inflammation are present


NAFLD has a prevalence of ~30% (range 10-46%) in the U.S. and a prevalence worldwide of 6-35% . NASH has a prevalence of 3-5% .

It is more commonly seen at ages 40-60. No gender predominance has been noted.

Clinical presentation

Often asymptomatic, although vague abdominal pain has been reported. Hepatomegaly has been reported in a minority of patients. Elevated liver enzymes (such as AST/ALT) may be present, especially with NASH.


The pathogenesis fo NAFLD is not well understood, but it has been associated with dysmetabolic conditions:

Radiographic features

The role of imaging is to demonstrate fat deposition in the liver, determine if cirrhotic changes are present, and to exclude other possible diagnoses. For general features of fatty deposition in the liver, see diffuse hepatic steatosis.

Liver biopsy may be needed in indeterminate situations to establish the diagnosis.

  • diffuse hypoattenuation of the liver relative to the spleen
    • non-contrast liver attenuation of <40 HU is specific, but not sensitive for diffuse hepatic steatosis
  • IP/OP: drop in signal intensity in liver on the out-of-phase sequence, compatible with intracellular lipid deposition

Treatment and prognosis

No definitive treatment has been established for NAFLD, but weight loss is thought to eliminate one of the factors contributing to the condition.

Patients who develop cirrhosis from NASH are treated similarly to other patients with cirrhosis.

Differential diagnosis

See also