Signs and symptoms

Because the liver is responsible for so many important functions, its impairment can affect the whole body . Many types of liver damage begin with inflammation, typically characterised by elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (ALT), two enzymes that break down amino acids in digested food. When the liver is damaged, these enzymes can leak out of liver cells and build up in the blood. A normal ALT level ranges up to 48 IU/l, while a normal AST level is up to 42 IU/l.

If cholestasis (clinically defined as retention of substances normally excreted into bile) occurs, blood levels of alkaline phosphatase may also rise, along with bilirubin, a pigment by-product of the breakdown of red blood cells. Elevated bilirubin can lead to jaundice (yellowing of the skin and whites of the eyes), dark-coloured urine, and pale stools.

Other early symptoms of liver toxicity may include fatigue, loss of appetite, malaise or flu-like feeling, upper abdominal pain or tenderness, and liver enlargement.

As liver damage progresses, scar tissue can build up. Blood flowing through the liver can back up, causing high blood pressure in the vessels that serve the liver. This can lead to development of varices (stretched and weakened veins) in the oesophagus and stomach, which may burst and cause internal bleeding. The feet and ankles may swell and fluid may accumulate in the abdominal cavity.

If the liver is unable to produce enough blood-clotting proteins, easy bruising and bleeding may occur. If it is unable to filter out toxins and metabolic by-products, these may build up and cause itching, brain damage, and coma. End-stage liver disease results in death if a liver transplant is not performed.

In rare cases, drug-related hepatotoxicity can cause acute fulminant liver failure, a life-threatening condition that has a high mortality rate unless a transplant is performed.