The liver: a vital organ
The liver is an important organ situated in the upper part of the abdomen. It has several functions.
It is responsible for manufacturing many proteins required for the normal functioning of the body, such as proteins which enable our blood to clot when we have a cut. It manufactures bile which is important in fat digestion. The liver also helps to process and gets eliminate waste products and toxins from the blood stream and the body.
It is an important organ for the breakdown of chemicals including the medicines we consume. It also helps in the breakdown of red blood cells converting the haemoglobin in the red blood cells into bilirubin and which is then excreted through the bile.
How can I tell if my liver is not OK?
Despite the liver’s importance, patients with liver disease often do not have signs or symptoms. This is because the liver has excess functional capacity. Signs and symptoms of impaired liver function will manifest only when the liver function is reduced by more than half.
Very often, one discovers that the liver is not quite normal when abnormalities in the liver tests are found. While abnormalities in these tests usually mean that something is happening in the liver, none of these tests are specific for the liver and diseases outside the liver may cause changes in these tests.
The protein and albumin levels reflect the ability of the liver to make proteins. A reduction in protein and albumin occurs as the liver function deteriorates and the liver is no longer able to manufacture proteins. However, protein and albumin levels may also occur in patients with severe infections or if proteins are lost in the urine or stools.
The bilirubin level reflects the liver’s ability to eliminate waste products from the body. However, high bilirubin levels may also reflect a blood disorder which causes increased breakdown of red blood cells and increased bilirubin production.
The alanine transaminase and aspartate transaminase (AST) are proteins found inside liver cells. Increased levels could mean the presence of a liver disease which damages liver cells causing the release of these proteins into the bloodstream. However, AST is also found in muscles cells and may be high in patients with damage to skeletal or cardiac muscle damage.
Alkaline phosphatase is an enzyme which is found in the liver and the bile ducts. Increased alkaline phosphatase often reflects the presence of either liver or bile duct disease. However, this is a protein which is also found in the bone and the intestines. Fractures and diseases affecting the bone also cause increased levels of alkaline phosphatase.
The gamma glutamyl transferase (GGT) is an enzyme which is found in the liver and is elevated in liver diseases. It is often used in conjunction with the alkaline phosphatase to determine that an elevated alkaline phosphatase level is caused by liver disease. However, the GGT is also elevated in diseases of the bile duct and the pancreas.
The other signs and symptoms of liver disease occur only when the liver starts to fail and is unable to carry out its function. This often occurs only late in the course of disease. The most famous sign of liver disease is jaundice, where the white of the eyes and the skin turn yellow. This is caused by an accumulation of bilirubin in the body because the liver can no longer eliminate it as it begins to fail.
Jaundice may be acute and temporary, as in the case of acute hepatitis A infection, where the liver damage is transient and the jaundice will reverse once the liver recovers. However, in patients with chronic liver disease where there is ongoing and continuing damage, such as hepatitis B and alcohol induced liver disease, the jaundice may persist for a longer period of time.
Abdominal and leg swelling
A patient whose liver fails will accumulate fluid in the abdomen and in the legs. The leg swelling often starts in the feet and more of the legs will become affected when the function of the liver worsens and fluid accumulation increases. Abdominal swelling is often not obvious initially. However, as it becomes worse, the patient’s abdomen will become more prominent and the umbilicus may also start turning outwards.
The liver plays an important role in removing chemicals and toxins from the bloodstream. These may be produced by the bacteria in our gut and which is then absorbed into the bloodstream, or they may be produced when the body breaks down cells and proteins. As the liver function deteriorates, the liver is unable to remove toxins from the bloodstream quickly enough. High concentrations of toxins like ammonia can affect the brain which will cause drowsiness. This is known as hepatic encephalopathy.
The liver manufactures some of the proteins important for blood clotting. In patients with chronic liver disease whose liver function is deteriorating, the liver’s ability to make these blood clotting proteins is also reduced. Patients will then bleed more easily resulting in bruises forming with even minor trauma.
Abdominal discomfort is an uncommon symptom in patients with liver disease. The liver tissue itself does not have any nerve endings and so very often no pain or discomfort is experienced. However, nerve endings are found in the capsule surrounding the liver and when the liver swells up very quickly, stretching of this capsule may result in discomfort or pain in the upper abdomen. An example of this would be the swelling of the liver in patients with acute hepatitis A.
None of the blood test abnormalities, symptoms or signs are specific for liver disease. Should one have any suspicion that the liver is abnormal, the family doctor should be consulted and appropriate tests done. Appropriate referrals can then be made should these suspicions be true.
Article reviewed by Dr Ling Khoon Lin, gastroenterologist at Mount Elizabeth Hospital