What is fatty liver? Fatty liver refers to a liver disease characterized by accumulation of fatty acids and triglycerides in liver cells (hepatocytes). Alcohol is a common cause of fatty liver, and is a factor that should always be considered in a patient with fatty liver. In this article we will refer to fatty liver not associated with consumption of alcohol. Fat accumulation in hepatocytes can lead to liver inflammation, with the possibility of developing fibrosis and ultimately end up in chronic liver damage (or cirrhosis).
Fatty liver is known in several ways:
- Fatty liver: A general term. When it is not because alcohol is known as nonalcoholic fatty liver disease (NAFLD).
- Liver steatosis: Accumulation of fat in the liver, synonymous of fatty liver.
- Nonalcoholic steatohepatitis: When the accumulation of fat in the liver is also accompanied by an inflammatory process. Non-alcoholic steatohepatitis is abbreviated NASH.
- Metabolic steatohepatitis: It has been proposed to call this disease metabolic steatohepatitis (MESH).
The cause of the accumulation of fat in the liver are not known with certainty, but there are some mechanisms that have proved very important in the development of the disease:
- Insulin resistance.
- Oxidative stress.
- Release of cytokines.
The occurrence of fatty liver is extremely common. This disease is associated with the following risk factors:
- Female sex.
However, it is increasingly common to find people with fatty liver without these risk factors. Not all people with fatty liver will develop complications or chronic liver damage.
In the general population, the prevalence of fatty liver is around 20 to 30%.
Fatty liver is often asymptomatic and only discovered after an ultrasound showing the liver more refractive (“bright”). The other way to get the diagnosis is through the discovery of elevated aminotransferases (transaminases) found in a routine blood test or some other reason. Some people complain of mild to moderate abdominal pain in the right upper quadrant (the area where the liver is located). Only a small percentage of patients develop symptoms of liver failure.
Diagnosis and evaluation
The diagnosis of fatty liver is based on the findings of liver biopsy. This shows fat accumulation in hepatocytes, and there may also be varying degrees of inflammation and fibrosis.
Although liver biopsy is the only test that ensures the diagnosis and is generally a low risk procedure, not all people with suspected diagnosis of fatty liver are subjected to this examination. It is customary to make a presumptive diagnosis of fatty liver disease in someone with suggestive images (ultrasound, CT or MRI). Liver biopsy is, however, the only test that differentiates between “simple steatosis” (fat accumulation) and ”steatohepatitis” (fat associated with inflammation and fibrosis).
Some people with fatty liver also have elevated transaminases or aminotransferases in the blood (SGOT and SGPT, also known as ALT and AST). In such cases it is important to rule out other causes of liver inflammation, such as infection by hepatitis B virus and hepatitis C, hemochromatosis and autoimmune hepatitis.
Prognosis and consequences
Most people with fatty liver will not develop severe disease consequences. Approximately 20% of the subjects may have some degree of hepatic fibrosis in the liver biopsy, which can lead to higher grades of the disease, including cirrhosis and liver cancer. Fatty liver is probably the most common cause of cryptogenic cirrhosis (cirrhosis with no clear cause).
Treatment of fatty liver consists primarily in losing weight and increasing physical activity. Obesity and overweight, the main risk factors are modifiable through changes in lifestyle. Other recommendations include avoiding alcohol and unnecessary drug (medication) use.
In those who are in advanced stages of disease (inflammation or significant hepatic fibrosis) some drugs may help, such as antioxidants (vitamin E) or insulin-sensitizing agents. The use of pioglitazone, which has shown benefits normalizing aminotransferases and liver histology, is still somewhat controversial.