Jaundice refers to yellow discoloration of the skin which occurs when there is too much bile pigment (bilirubin) in the blood. It is often first noticed in the whites of the eyes.
Bilirubin can build up in the blood for many reasons. There are three main groups: obstruction, hemolysis and liver disease.
Obstructive causes are easy to understand. The liver normally produces about 1 liter (approx. 34oz) of bile each day, which is secreted (passed) into the bile duct system and stored in the gallbladder. The bile duct empties through the sphincter of Oddi (a small tight band) at the papilla of Vater (a small opening) in the duodenum, to help in digestion. Obstruction anywhere in this drainage system causes the blood levels of bilirubin to increase, resulting in obstructive jaundice.
Common causes of obstructive jaundice include gallstones and tumors of the pancreas or bile duct. With gallstones, jaundice may be intermittent if the stone is not firmly stuck. Rarer causes of obstructive jaundice include parasites such as worms, scarring from previous surgical procedures, bile duct inflammations (such as primary sclerosing cholangitis), and, in infancy, congenital malformations of the bile duct system.
Obstructive jaundice is often accompanied by severe irritation of the skin, due to a buildup of other bile constituents (salts) in the blood. In addition, because the bile is not entering the small intestine, urine and bowel movements will be unusually pale in color (and the bowel movements may also be bulky and smelly because fats are not absorbed properly).
Much of our bilirubin is derived from the breakdown of red blood cells (which have a life of about 120 days). When breakdown occurs too fast (hemolysis), the amount of bilirubin produced may flood and/or clog in the liver and drainage system, resulting in jaundice. The bilirubin is in a different form compared with that due to obstructive causes, since it has not been connected to other substances in the liver.
The other main cause of jaundice is disease of the liver itself. The normal mechanisms for taking the bilirubin out of the blood and transporting it into the bile duct system becomes disturbed by disease or inflammation. Common liver diseases include infections such as hepatitis, and chronic conditions such as cirrhosis.
Jaundice looks odd, and makes you feel bad. It is not itself dangerous (apart from the special jaundice of premature infants). However, it is an important sign that there is something seriously wrong which requires investigation and treatment.