Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are are most common liver disease in western countries; now, the incidence is increasing in the Middle East, Far East, Africa, the Caribbean, and Latin America.
NAFLD and NASH represent a major global public health problem, which is pandemic and affects rich and poor countries alike.
NAFLD is a condition, where there is excessive accumulation of fat in the form of triglycerides (steatosis) in the liver.
|Micrograph demonstrating marked (macrovesicular) steatosis in non-alcoholic fatty liver disease. Masson's trichrome stain. (Photo credit: Wikipedia)|
NAFLD may progress to NASH, where there occurs liver cell injury and inflammation in addition to the excessive fat accumulation.
Progression of NAFLD to NASH dramatically increases the risks of cirrhosis, liver failure, and hepatocellular carcinoma.
The exact cause of NASH has not been elucidated, however it is most closely related to insulin resistance, obesity, and the metabolic syndrome. But, it not at all a rule that all patients with these conditions will lead to NAFLD/NASH, and vice-versa.
NAFLD and NASH are the diseases diagnosed by method of exclusion of other conditions. Not every person with fatty liver needs aggressive therapy.
Diet and exercise should be instituted for all patients. Patients with NASH or risk factors for NASH may additionally be treated with high dosages of Vitamin E or pentoxifylline, experimental therapy. These should only be tried in patients who fail to achieve a 5% to 10% weight reduction over 6 months to 1 year of successful lifestyle changes.
Bariatric surgery may be considered in patients in whom the above approaches fail, and it should be performed before the patient becomes cirrhotic.
Liver transplantation is successful in patients who meet the criteria for liver failure; however, NASH may recur after transplantation and is likely to be denied to patients with morbid obesity.
As a Clinician may not be able to diagnose NASH on the basis of clinical data alone, in a similar way the pathologist may not be able to document the histological lesions of steatohepatitis and reliably distinguish those of non-alcoholic origin from those of alcoholic origin.