Non-alcoholic Fatty Liver Disease

Functions of the liver

The liver is in the upper right part of the tummy (abdomen). It performs various functions:

1.It makes proteins that are essential for blood to clot(clotting factors).

2.It helps to process fats and proteins from digested food.

3.It stores glycogen, a chemical made from sugars. When required, glycogen is broken down into glucose which is released into the bloodstream.

4It makes bile which passes from the liver to the gut and helps to digest fats.

5.It helps to remove or process alcohol, poisons and toxins from the body.

6.It processes many medicines which one may take.

Understanding non- alchoholic fatty liver

Non-alcoholic fatty liver disease (NAFLD) describes a range of conditions caused by a build-up of fat within liver cells. It is helpful to divide NAFLD into four stages:

Simple fatty liver (hepatic steatosis). Normally, very little fat is stored in liver cells. Simple fatty liver means that excess fat builds up (accumulates) in liver cells. For most people, simple fatty liver does not cause any harm or problems to the liver. However, in some people it can progress to more severe forms of NAFLD.

Non-alcoholic steatohepatitis (NASH).

In this condition the excess fat in the liver cells is associated with, or may cause, inflammation of the liver. (‘Steato’ means fat, and ‘hepatitis’ means inflammation of the liver). This is much less common than simple fatty liver.

Fibrosis. Any form of persistent hepatitis, including steatohepatitis, may eventually cause scar tissue(fibrosis) to form within the liver. When fibrosis first develops often there are many liver cells that continue to function quite well.

Cirrhosis. This is a serious condition where normal liver tissue is replaced by a lot of fibrosis. Thestructure and function of the liver are badly disrupted. It is, in effect, like a severe form of liver fibrosis. Many liver conditions can lead to cirrhosis, including NAFLD. Severe cirrhosis can lead to liver failure.

NAFLD occurs in people who do not drink excessive amounts of alcohol and so alcohol is not the cause. Most people with NAFLD have simple fatty liver. Only a minority progress to develop NASH. And, only a minority of people with NASH progress to cirrhosis. It is not clear why some people with simple fatty liver progress to the more severe forms of NAFLD, and most do not.

More types of fatty liver

A condition similar to NAFLD can affect people who do drink a lot of alcohol. Another fatty liver condition called fatty liver of pregnancy 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 being sick (vomiting), tummy (abdominal) pain and jaundice. Jaundice is a condition caused by a build-up in the body of a chemical called bilirubin, where skin and other body parts turn a yellow colour.

Proness to non-alcoholic fatty liver disease

NAFLD is the most common persistent (chronic) liver disorder. It is thought to occur in about4 to 5 adults who are obese. However, most of these people have ‘simple fatty liver’ and not the more serious types of NAFLD.

The risk factors for developing NAFLD include:

Obesity. Most people with NAFLD are obese or overweight. However, the relationship between body fat and NAFLD, and factors that determine which people with obesity will develop NAFLD, are not clear. So, for example, some people who are only mildly overweight develop NAFLD. On the other hand, some people who are very obese do not develop NAFLD.

Diabetes. People with type 2 diabetes have an increased risk of developing NAFLD. However, there is no increased risk for those with type 1 diabetes.

Age. NAFLD is more common in people aged over 50 years. It is also more common in men. High blood pressure (Hypertension).

People with hypertension are at a greater risk of developing NAFLD.

High level of blood fats (Hyperlipedaemia). If you have high level of cholesterol and/or triglycerides in your blood then you have a higher risk of developing NAFLD.

Very rapid weight loss. For example, NAFLD develops in some people following surgery to reduce obesity. This may be due to rapid changes of fats and fatty acids in the blood that occur when weight loss is rapid.

Medicines. For example, methotrexate and tamoxifen can, rarely, cause NAFLD.

People with NAFLD have a higher chance of developing type 2 diabetes and cardiovascular disease which includes heart attacks and stokes. Also, as NAFLD is common, some people with NAFLD also have another liver disorder, and NAFLD can make the other liver disorder worse.

Indications of non-alcoholic fatty liver disease

Most people with simple fatty liver or NASH have no symptoms. However, some people with simple fatty liver or NASH have a nagging persistent pain in the upper right part of the tummy (abdomen), over an enlarged liver. You may feel generally tired if you have NASH. As most people do not have symptoms, the diagnosis is often first suspected when an abnormal blood test result occurs.

A small proportion of people with NAFLD develop cirrhosis.

Identification of non-alcoholic fatty liver disease

There is no simple test that can confirm NAFLD. Blood tests called Liver Function Tests (LFT) measure the blood levels of certain chemicals (enzymes) made by the liver cells. An abnormal pattern of LFTs may suggest that presence of NAFLD. However, many other liver conditions can cause abnormal LFTs. Therefore, if there are abnormal LFTs, a doctor will usually then do various other blood tests to rule out other causes of liver problems. For example, blood tests to detect various germs (viruses) and other liver-related chemicals.

LFTs are tests that are done for various reasons. Therefore, NAFLD is often first suspected when an abnormal result occurs when the tests are done for an unrelated reason.

A scan of the liver can be helpful. For example, an ultrasound scan, CT SCAN or MRI SCAN . The scan can show an enlarged liver compatible with the diagnosis of NAFLD. However, a scan cannot definitely diagnose NAFLD.

The diagnosis of NAFLD is usually based on the abnormal LFTs and scan being compatible with NAFLD, and ruling out other causes of liver problems. If there is doubt about the diagnosis, a specialist may arrange a small sample (biopsy) to be taken from your liver. This can be looked at under the microscope and can show the extent of any fatty accumulation, inflammation, scarring, etc, in the liver.

However, a liver biopsy is not routinely done when simple fatty liver or NASH is the likely diagnosis, as there is some risk involved when doing a liver biopsy. A liver biopsy is mainly done if the diagnosis is in doubt, or if there is concern that cirrhosis has developed.

Therapies for non-alcoholic fatty liver disease

Weight reduction

Most cases of NAFLD are linked to being obese or overweight. There is good evidence that a programme of gradual weight loss and regular exercise can reduce the amount of fat in the liver. So, if one has simple fatty liver or mild NASH, this may prevent or delay the progression of NAFLD. It may reduce one’s chance of developing cirrhosis – a condition where normal liver tissue is replaced by a lot of scar tissue (fibrosis).

In some people who are very obese, obesity surgery may be considered, as studies have shown that this may help to improve NASH.

Handling linked conditions and risk factors

One’s risk of developing cardiovascular disease is increased on having NAFLD. In fact, people with NAFLD are actually more likely to become ill and die from cardiovascular diseases such as heart attacks than from a liver problem. Therefore, one’s doctor is likely to stress the importance of reducing any ‘lifestyle’ risk factors that increase the risk of developing cardiovascular disease. For example not smoking, keeping one’s weight in check, taking regular exercise and eating a healthy balanced diet. Treating high blood pressure (hypertension) and a high cholesterol level (hyperlipidaemia) is suggestible.

If one has diabetes, then good control of blood sugar (glucose) level is thought to help reduce the risk of NAFLD getting worse.

It is also advised that one does not consume any alcohol. NAFLD (by definition) is not caused by alcohol. However, even modest amounts of alcohol may make NAFLD worse.

Medication that affects the liver itself

Various medicines have been suggested as possible treatments for NAFLD. However, there is little research evidence to say that any medicine works very well. For example, for NASH, no treatment has been proved to stop or reverse the inflammation. Various medicines are currently being trialled in different studies. One or more medicines may emerge as treatments in the future.

Prognosis

For most people with NAFLD, the condition does not progress beyond simple fatty liver or NASH. Cirrhosis – a condition where normal liver tissue is replaced by a lot of scar tissue (fibrosis) – and serious liver problems do not develop in most cases. The condition may reverse and even go away by weight loss, if one is overweight or obese or with good control of diabetes (if diabetes is the cause).

However, fatty liver does progress to NASH in some people, and NASH progresses to cirrhosis in some people. It is not clear why some people with NASH, and not others, progress to cirrhosis. Cirrhosis is very serious, can lead to liver failure and be fatal.

It is estimated that, on average:

About 2 in 100 people with simple fatty liver progress to cirrhosis over 15-20 years.

About 12 in 100 people with NASH progress to cirrhosis over about 8 years.

So, most people with NAFLD do not develop serious liver disease. However, because NAFLD has become very common in recent years (probably because of the epidemic in obesity), NAFLD has become a common cause of cirrhosis.

But one must also remember that, cardiovascular disease is the most common cause of illness and death in people with NAFLD. Perhaps the most important ‘take home message’ if one is diagnosed with NAFLD is not to focus too much on one’s liver. But, to concentrate on reducing any risk factors for developing cardiovascular problems. Life style changes like diet, weight loss, Exercise, Quitting smoking & abstinance from alcohol.

CONCLUSION

Non-alcoholic fatty liver disease (NAFLD) is a range of conditions caused by a build-up of fat within liver cells. It is very common and in many cases is linked to being obese or overweight. Most people with NAFLD do not develop serious liver problems. The building -up of fat in the liver can lead to serious liver disease . In some people. However,there is an increased risk of developing cardiovascular problems such as heart attacks and stroke, in all people with non-alchoholic fatty liver disease.

If one is obese or overweight, a main treatment advised for NAFLD is usually gradual weight loss and regular exercise. This not only helps with NAFLD but will helps reduce one’s risk of developing cardiovascular problems. Other treatment methods are discussed below.