Yellow colouring of skin, mucous membrane and bodily fluids by an excess in the bloodstream of bilirubin, the colouring matter of bile. Before it is discharged from the body, bilirubin follows a course which jaundice interrupts in some way. It circulates as follows: bilirubin is a waste product of the breakdown of old red blood cells, which live for approximately 110 days. It is absorbed by the liver and converted into a water-soluble form, then discharged into the bile, which passes through the gall bladder and bile ducts, then to the intestine, where it gives faeces their characteristic brown colour. The most important causes of jaundice are: increased breakdown of blood (haemolysis), with resultant increase in bilirubin level; lack or shortage of liver enzymes, without which bilirubin cannot be converted (certain forms of neonatal jaundice); decreased discharge of bile as a result of liver conditions (such as hepatitis or cirrhosis of the liver); blockage of the bile duct (increasing obstruction by gallstones , cancer of the gall bladder or tumour of the pancreas). A doctor must always be consulted if jaundice occurs, to establish the cause by checking associated symptoms (fever, general malaise, pain, pharyngitis) and clinical history (use of medication and alcohol, existing cirrhosis or other conditions). In addition to these symptoms, colourless faeces, dark urine and itching point to blockage of the bile duct, in that bilirubin is converted in the liver but cannot reach the intestine, and is passed in the urine. If blood is being broken down more rapidly the faeces are extra-dark, because the quantity of bilirubin increases. Blood tests are important: an increase in liver enzyme level points to inflammation or restricted discharge. Liver biopsy can furnish more information. Treatment is directly dependent upon the cause, which must be treated to control the jaundice.