Diagnosing liver disease
Chronic liver disease is seen throughout the world. According to the World Gastroenterology Organisation, deaths from cirrhosis are increasing and is expected to become the 12th leading cause of death in 2020.
Estimates suggest that about 34-46% of the general adult population and 70-80% of obese people living in western countries have some degree of non-alcoholic fatty liver disease – the most common liver problem worldwide.
Accurate statistics on liver disease in South Africa are difficult to find, but a large European study conducted at the behest of the European Association for the Study of the Liver, and published in the Journal of Hepatology, revealed the four major causes of liver disease to be alcohol consumption, viral hepatitis B and C, and metabolic syndromes related to obesity.
Africa has one of the highest rates of liver cancer in the world. This is linked to the high number of people chronically infected with hepatitis B virus. About 5% of South Africans have chronic hepatitis B virus infection. Less than 1% have hepatitis C and alcohol consumption is very common.
How is liver disease diagnosed?
As there are so many different causes and types of liver disease, the specific disease can be difficult to diagnose. The symptoms of liver disease also overlap with those of other conditions, which means that they’re sometimes overlooked.
People who are born with a congenital liver disease usually start to develop symptoms early in life. However, acquired liver diseases frequently have no or few symptoms in the early stages, so they can be easily missed. This is the reason why liver disease is often only diagnosed when the condition is already serious, or even irreversible.
Signs of possible liver disease include jaundice, a swollen abdomen, or tenderness in the area of the liver.If your doctor thinks you may have liver disease, he or she will try to determine which risk factors you may have been exposed to.
This could include:
- Prescription or over-the-counter medication usage
- Past blood transfusions
- Sexual activity
- Alcohol consumption
- Occupational exposure to blood products
- Exposure to toxic chemicals
- Family history of liver disease
- Travel to high-risk areas
- Use or experimentation with injection drugs
In order for treatment of liver disease to have a chance of success, your future exposure to risk factors needs to be reduced, if possible. This can be done by controlling factors such as alcohol consumption and drug use, but little can be done about a viral infection that’s already present.
Liver function tests
Liver function tests are blood tests that can help your doctor to diagnose liver disease or damage, and also monitor your response to treatment. These tests measure how well your liver is performing its normal functions, as well as the levels of enzymes that liver cells release in response to damage or disease. Note that abnormal liver function test results don't always indicate liver disease.
Common liver function tests include:
Alanine transaminase (ALT) Aspartate aminotransferase (AST)
The liver releases this enzyme when damaged.
This tests how well the liver is producing albumin, a protein.
This tests how well the liver is getting rid of bilirubin, a pigment that occurs as red blood cells are broken down. When elevated, people are jaundiced (yellow)
The symptoms of hepatitis, if present, will usually lead a healthcare professional to suspect the disease early on.
Blood tests can be done to confirm that there’s hepatitis and how severe it is. These tests can also give some clues as to whether the cause is viral, or not.
However, doctors cannot tell one type of viral hepatitis from another without specific tests for the different viruses. Laboratory diagnosis of hepatitis A and B requires very straightforward blood tests. In the case of hepatitis B, some additional tests are available that can give information about whether this is a recent or chronic infection, and how active the virus is.
An early or recent hepatitis C infection may not be detected so readily, since the usual test only becomes positive when antibodies are produced by the immune system several weeks or months into the illness. Therefore, a specialised polymerase chain reaction (PCR) test for the hepatitis C virus may be required.
Have a look at this summary of the tests used to diagnose hepatitis A, B and C. The most important tests are marked in bold:
Hepatitis A IgM antibody
If positive, this indicates current or recent infection.
Hepatitis A IgG antibody
In the absence of hepatitis A IgM antibody, this indicates past infection with hepatitis A and immunity.
Hepatitis B surface (s) antigen
If positive, the person has hepatitis B infection and is infectious.
Hepatitis B early (e) antigen
This antigen is a marker of active infection. It’s usually found in the earlier part of the infection history.
Hepatitis B early (e) antibody
This antibody is present when the e-antigen is no longer present.
Hepatitis B core IgM antibody
This usually indicates recent rather than chronic infection.
Hepatitis B core IgG antibody
This is found in anyone who is or has been infected with hepatitis B.
Hepatitis B surface (s) antibody
This indicates immunity to hepatitis B.
Hepatitis C antibody
This indicates infection, either current or recent, but the test may be negative in early infection.
Hepatitis C PCR
If positive, this indicates current infection.
During a liver biopsy, a thin needle is inserted into the liver to remove a portion of the liver tissue. The tissue is then examined under a microscope.
A liver biopsy is often used to determine the level of excess fat in the liver and whether chronic hepatitis, metabolic liver diseases such as Wilson’s disease (an excess of copper), haemochromatosis (an excess of iron) or cancer is present.
Liver biopsies are usually only considered after blood tests and imaging tests have failed to provide your doctor with the necessary information to make an accurate diagnosis.
A variety of imaging tests
Ultrasound uses sound waves to produce images, but it cannot show blood flow. For this, Doppler ultrasound, which measures and visualises actual blood flow, is used.
Doppler ultrasound is a non-invasive, widely available imaging test that can provide information about the appearance and the blood flow of the liver. It should be the first test to be performed if liver disease is suspected, as it’s the least expensive of the imaging tests. It also doesn’t pose a radiation exposure risk.
Transient elastography, commercially known as FibroScanR, is a state-of-the art technique that uses a modified ultrasound probe to measure the stiffness of the liver. It’s an effective and non-invasive way to tell whether the liver has fibrosis (the first stage of liver scarring). It is now available in South Africa.
CT and MRI scans
Computerised axial tomography (CT) and magnetic resonance imaging (MRI) are generally not very good at detecting changes in the form and structure of the liver affected by early cirrhosis. These tests are also very expensive. They’re generally only used to determine changes in the liver in advanced cases of liver disease, or to further image a growth in the liver.
Treating liver disease
Reviewed by Dr Mark Sonderup, B Pharm, MB ChB, FCP (SA). Senior Specialist, Division of Hepatology, Department of Medicine, University of Cape Town and Groote Schuur Hospital. March 2018.