Chronic liver disease: introduction

Description of the liver and its functions

The liver is the largest organ in the body, weighing approximately 1.5kg and is vital for life. It is located in the upper right quadrant of the abdomen tucked underneath the ribs. It is responsible for many (over 500) important functions such as processing nutrients, breakdown of toxins and production of essential proteins. It processes digested food from the intestine by breaking it down into glucose and converting into glycogen for energy storage. Another key function is the removal of waste products from the blood. Some are concentrated into bile which is stored in the gallbladder and then is discharged into the duodenum. Bile also plays a part in digestion by emulsifying fats. The liver plays an important role in combating infection and in protein synthesis and metabolism.

Chronic Liver Disease

There is little evidence that the liver ages and it can function well into old age if disease free. It is also able to naturally regenerate lost tissue. Chronic liver disease is characterised by scarring and destruction of the liver tissue. Early changes, such as 'fatty liver' (a build up of fat in the liver cells) can progress via inflammation (hepatitis) and scarring (fibrosis) to irreversible damage (cirrhosis). At this point, the liver will not be able to regenerate itself though further damage can be averted. Most chronic liver disease is symptomless ('silent') and when symptoms do develop, they are often vague such as tiredness, weakness, loss of appetite and nausea. Once the liver begins to fail (or decompensate) symptoms and signs include bruising easily; yellow skin (jaundice); itching and accumulation of fluid in legs (oedema) or the abdomen (ascites). Causes of death from cirrhosis include development of liver failure, brain damage (encephalopathy), catastrophic internal bleeding (oesophageal varices) and also primary liver cancer. Most of cases of hepatocellular carcinoma, the commonest primary liver cancer, occur in patients with cirrhosis.