Fatty Liver Disease

What does the liver do?

The liver is in the upper right part of the abdomen. It has many functions which include:

• Storing glycogen (fuel for the body) which is made from sugars. When required, glycogen is broken down into glucose which is released into the bloodstream.
• Helping to process fats and proteins from digested food.
• Making proteins that are essential for blood to clot (clotting factors).
• Processing many medicines which you may take.
• Helping to remove or process alcohol, poisons and toxins from the body.
• Making bile which passes from the liver to the gut and helps to digest fats.

What is fatty liver disease?

Fatty liver disease covers a range of conditions where there is a build-up of fat in the liver cells. The liver cells (hepatocytes) normally contain some fat and related fatty chemicals (triglycerides, fatty acids, etc). Excess fat is normally passed out of liver cells, into the bloodstream, and then taken up and stored in fat cells (adipose cells) throughout the body.

In fatty liver disease, excess fat builds up in liver cells. This is thought to happen if there is some problem or disruption in the normal processing of fat and related fatty chemicals in the liver cells. (Eating fatty food by itself is not a cause of fatty liver disease.)

Simple fatty liver (also called 'hepatic steatosis')
Simple fatty liver is common. (In the US it is thought to occur in 1 in 4 adults.) Simple fatty liver is present when the fat content inside liver cells makes up more than 5-10% of the liver's weight. Simple fatty liver is not associated with serious damage or harm to the liver. It seems that the fat just builds up harmlessly in liver cells. It can occur for no apparent reason. However, most people with simple fatty liver have other conditions where fatty liver is a complication. Mainly:

• Alcohol excess. Many cases develop in people who drink more alcohol than the recommended limits. Over half of people who drink heavily develop simple fatty liver.
• Obesity. Most people with simple fatty liver who do not drink excess alcohol are obese. The factors that determine who will develop fatty liver are not known. Some mildly overweight people develop fatty liver while some who are severely obese do not.
• Diabetes.

There is usually no symptoms caused by the fatty liver itself. (The cause of the fatty liver such as alcohol excess, diabetes, etc, may cause other symptoms.) The liver may enlarge and cause mild pain over the liver area. A doctor may feel an enlarged liver when examining the abdomen.

Steatohepatitis
In this condition the excess fat in the liver cells is associated with, or may cause, inflammation of the liver. This is called or steatohepatitis (steato means fat, and hepatitis means inflammation of the liver). This is much less common than simple fatty liver. Any form of persistent hepatitis, including steatohepatitis, may eventually cause scarring (cirrhosis) of the liver. Cirrhosis is a serious liver condition (see separate leaflet called 'Cirrhosis').

There are two types of steatohepatitis:

• Alcoholic steatohepatitis. This is caused by drinking too much alcohol. Unless alcohol drinking is stopped it often progresses to cause cirrhosis.
• Non-alcoholic steatohepatitis ('NASH'). This is a steatohepatitis which is not caused by alcohol. The reason why NASH develops is unclear. No cause can be found in some cases, but in some cases it seems to develop as a complication of various problems, mainly:
  • Obesity.
  • Diabetes.
  • High lipid levels in the bloodstream (hyperlipidaemia).
  • Following jejunoilial bypass surgery for obesity.
  • In people who change weight relatively quickly (such as after a 'crash diet').
  Most people with NASH have no symptoms. Some may feel generally tired. Some have a nagging persistent pain in the upper right part of the abdomen, over an enlarged liver. In the small number of people with NASH who develop cirrhosis, symptoms of cirrhosis may develop several years after NASH first develops. (See separate leaflet called 'Cirrhosis'.)

Acute fatty liver of pregnancy
This is a rare, but serious condition of pregnancy. In this condition a lot of fat builds up in the liver cells and causes damage quite quickly. The cause is not known. Symptoms include vomiting, abdominal pain and jaundice. Both mother and baby are at risk of dying with this condition as it can cause liver failure. The condition usually develops towards the end of pregnancy. The treatment is to deliver the baby as soon as possible after the condition is diagnosed.

Other
Fat may accumulate in liver cells as part of various other conditions. For example:

• Malnutrition (especially in children with severe malnutrition called kwashiorkor).
• Inborn metabolic disorders of glycogen, galactose, tyrosine, or homocysteine.
• As a side-effect of some drugs.
• It can occur with various illnesses causing a fever.

Depending on the cause, the fat deposits in the liver cells may result in simple fatty liver, steatohepatitis, or liver failure.

How is fatty liver disease diagnosed?

Blood tests of liver function may show some abnormalities. Other tests such as ultrasound scan or CT scan may suggest a fatty liver disease. Various blood tests and other tests may be done to rule out other liver disorders such as viral hepatitis, autoimmune hepatitis, etc.

The only way to be certain of the diagnosis is to do a liver biopsy. A liver biopsy is when a small sample is taken to look at under the microscope. This can show the extent of any fatty accumulation, inflammation, scarring, etc, in the liver. See separate leaflet called 'Liver Biopsy'.

What is the treatment and outlook?

Simple fatty liver usually causes no problems and rarely progresses. However, as mentioned, it can be a 'marker' for heavy alcohol drinking, which if continued, can cause more serious problems. Simple fatty liver may reverse and go away by stopping alcohol (if alcohol is the cause), with weight loss (if obese), or with good control of diabetes (if diabetes is the cause).

For alcoholic steatohepatitis the treatment is to stop drinking alcohol if at all possible.

For NASH, no treatment has been proved to stop the inflammation. However, the outlook is usually good. Cirrhosis and serious liver problems do not develop in most cases. It is not clear why some people with NASH progress to cirrhosis. Probably the best ways to minimise the risk of developing serious liver problems are: slow weight reduction and exercise (if obese), a low fat diet, good control of diabetes (if diabetes is the cause). Also, it is best not to drink any alcohol, or only small amounts, to minimise this aggravating the condition. In the small number of cases where cirrhosis develops, the treatment and outlook is as for other causes of cirrhosis. See separate leaflet called 'Cirrhosis'.

Further help and information

British Liver Trust
2 Southampton Road Ringwood BH24 1HY
Tel: 0870 770 8028   Web: www.britishlivertrust.org.uk

© EMIS and PIP 2006   Updated: August 2006