Nonalcoholic steatohepatitis (NASH)
Nonalcoholic steatohepatitis (NASH) is a condition characterized by inflammation and the accumulation of fat and fibrous tissue in the liver. Although similar findings can be seen in patients who abuse alcohol, NASH occurs in those who do drink little to no alcohol. The exact cause of NASH is unknown.
Most affected people are between the ages of 40 and 60 years, although the condition can also occur in children over the age of 10 years. NASH is seen more often in women than in men.
CONDITIONS ASSOCIATED WITH NASH
Although the cause of NASH is unknown, it is most frequently seen in persons with a number of other conditions.
Obesity
Diabetes mellitus
Hyperlipidemia
Insulin resistance
Factors that affect metabolism
Abdominal surgery
Drugs and toxins
Other conditions
Certain other medical conditions have also been linked to NASH. These conditions include Wilson's disease , Weber-Christian disease , abetalipoproteinemia , and diverticula of the small intestine.
SYMPTOMS
Most people with NASH have no symptoms. Very rarely, NASH is diagnosed after patients consult their doctor because of fatigue, a general feeling of being unwell, and vague discomfort in their upper right abdomen, although the relationship of these symptoms to NASH is unclear.
DIAGNOSIS
NASH is most often discovered during routine laboratory testing and proven by a liver biopsy. Additional tests help confirm the presence of NASH and rule out other types of liver disease.
Medical history
A medical history may reveal conditions or events that have been associated with NASH, such as diabetes or abdominal surgery. In addition, a clinician may ask about risk factors for other forms of liver disease such as viral, drug-induced, or alcoholic hepatitis.
Physical examination
A physical examination may reveal an enlarged liver, but it is usually normal.
Liver function tests
Liver function tests determine blood levels of substances produced or metabolized by the liver. They can be helpful for diagnosing NASH and for differentiating NASH from alcoholic hepatitis. Levels of two liver enzymes (AST and ALT) are elevated in about 90 % of people with NASH.
Other blood tests
Additional blood tests are useful for ruling out other causes of liver disease. These usually include tests for viral hepatitis (hepatitis A, B, or C), and may include tests for less common cause of liver disease.
Imaging test
Imaging tests (such as ultrasound, CT scan, or magnetic resonance imaging) may reveal fat accumulation in the liver. Imaging tests are not used to diagnose NASH since they cannot differentiate it from other causes of liver disease that have a similar appearance.
Liver biopsy
Although other tests may suggest a diagnosis of NASH, liver biopsy is required to confirm it. A liver biopsy is also helpful for determining the severity of NASH and may provide clues about the future course of the condition. Sometimes, doctors will recommend gradual weight loss and watchful waiting for six months to one year before a liver biopsy; abnormal liver function tests return to normal after losing weight in some people.
TREATMENT
At this time, there is no treatment to cure NASH. Treatment aims to control the conditions that are associated with NASH, such as obesity, diabetes, and hyperlipidemia. Several experimental treatments with drugs that treat insulin resistance are being studied.
Vitamin E was used in NASH because of earlier reports suggesting it may reduce liver blood tests, but these results were not confirmed in later studies. Long-term vitamin E may also be associated with an increased risk for heart disease.
PROGNOSIS
Few factors have been useful in predicting the course of this condition, although features in the liver biopsy can be helpful. The good news is that NASH is a stable medical condition in most people.
However, NASH can progress in some people. One study that tracked liver damage over time showed that it improved in about 3 % of people, remained stable in 54 % of people, and worsened in 43 % of people .
Progressive liver damage can eventually lead to cirrhosis. Over a seven-year period, between 8 and 26 % of people with NASH develop cirrhosis. Older diabetic women may be at increased risk. People who have developed cirrhosis are at risk for eventually developing complications of cirrhosis , that may ultimately require liver transplantation.
