Non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease, sometimes abbreviated NAFLD, is a relatively common condition characterized by the build-up of fat in the liver of individuals who drink little if any alcohol. In its mildest form, NAFLD is considered benign; however, in severe cases, it can lead to liver failure. The condition is strongly linked to obesity as well as insulin resistance and is often considered a component of metabolic syndrome.
Definition & Facts
It is normal for the liver to contain a certain amount of fat; however, if fat comprises more than five to 10 percent of the liver’s weight, the individual may have fatty liver disease. NAFLD is a leading cause of chronic liver disease. The mildest form of NAFLD is steatosis in which fat accumulates in the liver, but there is no inflammation or scarring.
A more severe form of the disease, called nonalcoholic steatohepatitis or NASH, occurs when there are inflammation and damage to the liver cells in addition to the fat accumulation. NASH creates liver scarring and ultimately progresses to cirrhosis. Some experts believe that NASH will soon become the leading reason for liver transplants unless new treatments are discovered.
Symptoms & Complaints
- Gastrointestinal bleeding.
- An accumulation of abdominal fluid known as ascites.
- Mental changes due to encephalopathy caused by the inability of the liver to remove toxins from the body.
- Jaundice characterized by a yellowing of the skin and sclera.
- Liver cancer.
The most important factors in the development of NAFLD appear to be obesity and diabetes mellitus. When an individual has a large number of fat cells, the cells can become metabolically active and affect other tissues in the body. The cells start to produce proteins and hormones that can create insulin resistance. This is a condition in which cells are unable to utilize the insulin produced by the pancreas. The body attempts to compensate by producing more insulin in order to control glucose levels. Eventually, the body is unable to keep up with the demand, and the sugar can accumulate in the blood leading to diabetes and altering the liver’s metabolic processes.
An excess of fat cells also increases the amount of fatty acids in the bloodstream. The liver changes these fatty acids into stored fat. If metabolic processes are altered, the liver is unable to dispose of the fat, and it continues to accumulate. NAFLD does appear to run in families. The condition is also most prevalent among individuals who are middle-aged, obese, and have high cholesterol or diabetes. In rare cases, NAFLD can be caused by medications, malnutrition, rapid weight loss, autoimmune diseases, or viral hepatitis.
Diagnosis & Tests
NAFLD is suspected if an individual is also obese or diabetic. Simple fatty liver disease is often diagnosed incidentally during routine lab work to monitor for other health conditions or side effects from medications. The tests will show an increase in specific liver enzymes. The doctor may notice an increase in liver size during a physical examination.
If this is the case, the doctor may also order imaging studies, including a CT scan or ultrasound. If the doctor suspects a more serious form of the disease, they may request a liver biopsy to remove a tiny sample of liver tissue for closer examination. The procedure involves inserting a long needle through the skin to obtain a tissue sample. The sample is then examined under a microscope for evidence of inflammation and scarring that would suggest a diagnosis of NASH.
A detailed patient history is also an important component of diagnosis in order to rule out other causes of fatty liver disease, including excess alcohol consumption. Although the majority of individuals with fatty liver disease do not have the more severe form of the condition, it is important to make the distinction in order to identify and prevent possible complications, including cirrhosis. Individuals with diabetes, metabolic syndrome, or obesity are typically candidates for biopsy since they are at higher risk of developing NASH.
Treatment & Therapy
Treatment for NAFLD typically includes lifestyle changes, medications, and supplements. In severe cases, the individual may require surgery, including liver transplantation. Regular exercise and maintaining a healthy weight are extremely beneficial in treating NAFLD. Even a 10 percent decrease in body weight can help reduce liver fat and inflammation. The following medications and supplements are commonly used to treat NAFLD:
- Insulin sensitizers, including metformin and pioglitazone, are useful in combating insulin resistance and metabolic syndrome that can lead to fatty liver disease.
- Antioxidants, including vitamin E, may be beneficial in reducing liver inflammation and fibrosis in certain patients.
- Limited studies have shown that omega-3 fatty acids reduce liver fat levels and the risk of cardiovascular events in individuals with NAFLD.
- Individuals with metabolic syndrome may benefit from statins to treat elevated lipid levels. Although the main benefit is in lowering cholesterol levels, there is some evidence showing that there may be an incidental benefit to the liver.
Obese individuals undergoing bariatric surgery to lose weight often show a decrease in liver fat and inflammation, and the progression of the disease is slowed or stopped. Once the individual develops cirrhosis and its complications, the only treatment is transplantation.
NASH is expected to become the leading cause of liver transplantation due to the epidemic of diabetes and obesity in the United States. Unfortunately, the disease can recur in the new liver if the underlying causes of obesity and diabetes are not addressed.
Prevention & Prophylaxis