Liver disease



Last Review Date: February 01, 2018


Overview of the Liver

The liver is a vital organ located in the upper right-hand side of the abdomen. It is about the size of a football and weighs around 1 - 1.5 kg, It performs numerous functions for the body including converting nutrients derived from food into essential blood components, storing vitamins and minerals, regulating blood clotting, producing proteins and enzymes, maintaining hormone balances, and metabolising and detoxifying substances that would otherwise be harmful to the body. The liver also makes factors that help the human immune system fight infection, removes bacteria from the blood, and makes bile, which is essential for digestion.

Bile, a greenish-yellow fluid consisting of bile acids (or salts) and waste products, such as bile pigments, flows through small bile ducts inside the liver. The bile flows from these small ducts into larger ones, like streams into a river, eventually leading to the common bile duct. The cystic duct connects the common bile duct to the gallbladder. After eating, the gallbladder, a fist-sized organ that sits next to the liver and stores bile, releases bile into the small intestine where it helps to digest fats.


What is liver disease?

Liver disease is c aused by acute (recent) or chronic (long term or repeated) damage to the liver. This damage is usually because of infection, injury, exposure to drugs or toxic compounds, an autoimmune process, or by a genetic defect (such as haemochromatosis). Liver disease can also be categorised by the effect it has on the liver. Hepatitis is an inflammation of the liver, cirrhosis involves scarring and progressive cell death, stones are developed and form blockages, cancer is rare but can be life threatening. Genetic defects cause liver disease by preventing vital functions and by depositing damaging substances in the liver.

Hepatitis
There are two major forms of hepatitis: one in which the liver is damaged quickly (called acute hepatitis) and one in which the liver is damaged slowly, over time (called chronic hepatitis). While hepatitis can be caused by medications, toxins and autoimmune disease, it is most commonly due to infection by one of several viruses that mainly damage the liver called hepatitis viruses. These viruses have been named in the order of their discovery as hepatitis A, B, C, D, and E. [See Viral Hepatitis]

  • Hepatitis A occurs when the hepatitis A virus is taken through the mouth. An infected person’s hands can become contaminated after using the toilet and the virus is spread by direct contact, or by food, beverages and other objects that were handled by the infected person. It can also be spread through infected water and food and is especially common in children. Most infected people don’t even know they have been exposed to the virus.
  • Hepatitis B is fairly common, especially in Asia and Africa. In Australia, carrier rates are likely to be about 0.1 to 0.2 percent amongst Caucasians but can be as high as 10 percent in some Aboriginal communities. Hepatitis B can be spread by exposure to blood, through sexual relations, and from mother to baby. Symptoms of hepatitis B may be absent, mild and flu-like, or acute (see Signs and symptoms section above). Most people will get better without any treatment, but about 1-3% become chronically infected, able to continue to infect others, and often have chronic damage to the liver. Those with weakened or compromised immune systems are at an increased risk to become carriers (about 10%). Newborns are especially vulnerable, with over 90% becoming carriers if mother and baby are untreated.
  • Hepatitis C is passed the same way as hepatitis B. Hepatitis C is less common than B as a cause of acute hepatitis, but the majority of the people who contract it become chronically infected, able to spread the infection to others, and usually have chronic damage to the liver.
  • Hepatitis D and E are relatively rare.

Since the liver is responsible for the metabolism of alcohol, drugs, and environmental toxins, prolonged exposure to any of these can also cause hepatitis and/or cirrhosis. Medications (for example paracetamol), alcohol and some naturopathic remedies, have the potential to cause life threatening acute liver failure.

Cirrhosis
Anything that causes severe ongoing injury to the liver can lead to cirrhosis. It is marked by cell death and scar formation and is a progressive disease that creates irreversible damage. Cirrhosis is treated by trying to limit further damage; if it is caused by a virus or another treatable cause of liver injury, treating the cause can stabilise the disease and prevent deterioration in liver function.

People with cirrhosis have no signs or symptoms in its early stages. As it progresses, it can cause fluid build-up in the abdomen (called ascites), muscle wasting, bleeding from the intestines, easy bruising, enlargement of the breasts in men (called gynaecomastia), and a number of other problems. Liver function is monitored with such tests as albumin, prothrombin time, bilirubin, and other liver function tests. In extreme cases, liver transplantation may be needed.

Gallstones
Cholesterol and bile pigments (bilirubin) in the bile may form stones in the gallbladder, where bile is stored. These stones may or may not cause symptoms and problems, depending on their size and location. If present for a long time, they may damage the gall bladder and prevent it from working properly. This often causes a feeling of bloating and discomfort in the upper abdomen after meals, especially ones high in fat. The gallstones may block the duct that drains bile from the gallbladder, causing sharp pain to develop suddenly in the upper right part of the abdomen and, in many cases, leading to infection of the gallbladder and fever.

Obstruction
Gallstones, tumours, trauma and inflammation can cause blockage of the ducts draining the liver (bile ducts). When an obstruction occurs, bile and its associated wastes including bilirubin, accumulate in the blood and the patient’s skin and eyes can turn yellow (jaundice). Bilirubin in the urine turns it a dark brown colour, while lack of bilirubin in the intestines causes the stool to become a pale colour. Blood tests may show elevated levels of bilirubin, alkaline phosphatase (ALP), and other liver enzymes.

Obstruction of the hepatic vein, the vein from the liver, may also occur, reducing blood flow out of the liver. This obstruction may be due to tumours pushing against the vein or from a blood clot forming inside the vein. Obstructions may be chronic and cause few symptoms, but they can also be acute and life threatening. Some can be treated with drugs, others require surgery.

Fatty liver
Fatty liver causes liver enlargement, tenderness and abnormal liver function. The most common cause is excessive alcohol consumption. It is usually a reversible condition, resolving with abstention from alcohol. Another cause of fatty liver is NAFLD (non-alcoholic fatty liver disease) and NASH (nonalcoholic steatohepatitis), the most common chronic hepatitis not caused by viruses. While symptoms are usually fairly mild, it may cause cirrhosis. It is seen most commonly in overweight and diabetic individuals.

Liver cancer
Hepatitis and cirrhosis may lead to liver cancer in some cases, but cancer from other parts of the body that spreads to the liver is more common. People who have chronic hepatitis or cirrhosis may be checked on a regular basis for cancer, often with an alpha-fetoprotein (AFP) test and/or an ultrasound.

Genetic causes
Haemochromatosis is the most common genetic liver disorder. It involves excess iron storage and is usually diagnosed in adults. There are numerous genetic liver diseases that affect children. Most of the diseases involve a defective element that results in liver injury (such as biliary atresia, where the bile ducts are absent or too small) or a missing enzyme or protein that leads to damaging deposits in the liver (such as galactosaemia, the absence of a milk sugar enzyme, which leads to milk sugar accumulation; and Wilson’s disease, where copper builds up in the liver).


Signs and symptoms


Liver disease is often discovered during routine testing. It may not cause any symptoms at first or the symptoms may be vague, like weakness and loss of energy.

In acute liver disease, the most common symptoms are related increased bilirubin (including jaundice which is a yellowing of the skin and eyes, dark urine and light stools) along with loss of appetite, nausea, vomiting and diarrhoea. 

Chronic liver disease symptoms include jaundice, dark urine, abdominal swelling due to the accumulation of fluid (ascites), pruritus (itching), unexplained weight loss or gain, and abdominal pain: they may not be present until the disease has reached an advanced stage.


What tests are used to detect a problem with the liver?


Three types of tests are often used to detect liver disease; these tests either measure the levels of specific enzymes, bilirubin, or protein present in the test sample (usually a blood sample). Among the more common tests in these three categories are:


1. Enzymes
Enzymes are proteins that help cells do their work. When cells are injured, enzymes can leak into the blood at higher-than-normal levels. Four common enzymes used to detect liver disease are:

2. Bilirubin
A waste product made from old blood cells, it is a yellow compound that causes jaundice and dark urine when present in increased amounts. Two different tests of bilirubin are often used together, especially if a person has jaundice:

  • Total bilirubin – measures all the bilirubin in the blood
  • Conjugated bilirubin – measures a form made in the liver

3. Protein
One of the main functions of the liver is to make protein. Two important liver tests include:

  • Albumin – measures the main protein made by the liver and tells how well the liver is making this protein
  • Total protein – measures albumin and all other proteins in blood, including antibodies made to help fight off infections (antibodies are not made in the liver)

Doctors often use these tests together to tell whether liver damage has occurred and how severe it is. When ordered together, these 8 tests are called liver function tests.

Your Doctor may also order a test called "Prothrombin time" (PT) or "Inernationalised Normalised Ratio" (INR) which is a measure of how well your liver is making proteins.


Related pages

On this site
Tests: Liver function tests, ALP, ALT, AST, albumin, bilirubin, PT, AFP, GGT, total protein
Conditions: Alcoholism, hepatitis, haemochromatosis, Wilson’s disease

Elsewhere on the web
CDC: viral hepatitis
HepatitisAustralia
Gastroenterological Society of Australia
Better Health Channel: Liver explained
Healthdirect Australia: Liver diseases