Jaundice is a yellow discoloration in the skin, whites of the eyes and mucous membranes (e.g., inside the mouth). It results from high levels of the yellow pigment bilirubin in the blood. Jaundice is a sign of many disorders, particularly those that affect the liver or the flow of bile.

Red blood cells are constantly being broken down into different materials that the body can use for various functions. Heme (the part of the cell that carries iron) is broken down into bilirubin. The bloodstream carries the bilirubin to the liver, where it is processed and used as a component of bile.

Bile has many functions. It assists in the digestion and absorption of fats and helps eliminate certain waste products from the body, including bilirubin and excess cholesterol. Bile also helps the body absorb cholesterol, fats and fat-soluble vitamins. In addition, it stimulates the secretion of water by the large intestine to help move contents through the digestive system.

Bile leaves the liver through the hepatic duct (duct connected to the liver) and travels to and from the gallbladder through the cystic duct. The junction of the cystic and hepatic ducts forms the common bile duct, which transports bile to the first portion of the small intestine (called the duodenum).

Some bile flows directly from the liver into the duodenum. However, about half is stored in the gallbladder. When food enters the duodenum after a meal, nerve signals are sent to the gallbladder causing it to contract and release more bile into the duodenum. The food is digested and eventually eliminated by the large intestine. It is the bilirubin in the bile that gives stool its brown color.

There are three primary ways in which bilirubin builds up in the bloodstream:

• Conditions directly affecting the liver. These can interfere with its ability to process bilirubin. Cirrhosis and hepatitis are examples of liver conditions that can cause jaundice.
  
  
• Obstruction of the bile ducts (cholestasis). Gallstones are the most common cause of the buildup of bilirubin due to obstruction.
  
  
• The rapid breakdown of red blood cells (hemolysis). The excess level of bilirubin can overwhelm the liver. This is comparatively rare in adults but more common in newborns.

Any excess bilirubin that is not properly eliminated is eventually deposited in the tissues of the body. This is visible as the yellow discoloration called jaundice.