Jaundice, also known as icterus, is a term used to describe a yellowish tinge to the skin and sclerae (the white part of the eye) that is caused by hyperbilirubinemia (an excess of bilirubin in the blood). Body fluids may also be yellow. The color of the skin and sclerae varies depending on levels of bilirubin; mildly elevated levels display yellow skin and sclerae, while highly elevated levels display brown.
Note that this article is about jaundice. We have a separate article about infant jaundice.
Bilirubin (bil-ih-ROO-bin) is a yellow colored substance that is responsible for the yellowing of the skin and sclerae. Bilirubin is a waste product that remains in the bloodstream after the iron is removed from the hemoglobin, which is released from the degradation of erythrocytes (cells that contain hemoglobin and can carry oxygen to the body). When there is an excess of bilirubin it may leak out into surrounding tissues, saturating them with this yellow substance.
Bilirubin that is circulating freely in the blood is called unconjugated bilirubin. One of the liver’s functions is to filter out waste, such as bilirubin, from the blood. Once it is in the liver, other chemicals latch on to the bilirubin, creating a substance called conjugated bilirubin, which is secreted in bile (a digestive juice released by the liver) and then excreted. Bilirubin is what gives feces its brown color.
The modern English word “jaundice” is derived from the middle French word jaunisse.Jaun means “yellow” and -isse means “-ness”; hence the middle French word jaunisse, which means “yellowness”.
Types of jaundice
There are three main types of jaundice:
- Hepatocellular jaundice – a type of jaundice that occurs as a result of liver disease or injury.
- Hemolytic jaundice – a type of jaundice that occurs as a result of hemolysis (an accelerated breakdown of erythrocytes – red blood cells) leading to an increase in production of bilirubin.
- Obstructive jaundice – a type of jaundice that occurs as a result of an obstruction in the bile duct (a system of tubes that carries bile from the liver to the gallbladder and small intestine), which prevents bilirubin from leaving the liver.
Jaundice, not to be confused with infant jaundice, is usually a sign of an underlying disorder.
Causes of jaundice
Jaundice most often occurs as a result of an underlying disorder that either causes tissues to become over-saturated with bilirubin or prevents the liver from disposing of bilirubin.
Some underlying conditions that may cause jaundice are:
- Acute inflammation of the liver – may impair the ability of the liver to conjugate and secrete bilirubin, resulting in a buildup of bilirubin.
- Inflammation of the bile duct – may prevent the secretion of bile and removal of bilirubin, causing jaundice.
- Obstruction of the bile duct – prevents the liver from disposing of bilirubin, which results in hyperbilirubinemia.
- Hemolytic anemia – Production of bilirubin increases when large quantities of erythrocytes are broken down.
- Gilbert’s syndrome – an inherited condition that impairs the ability of enzymes (biomolecules that provoke chemical reactions between substances) to process the excretion of bile.
- Cholestasis-a condition in which the flow of bile from the liver is interrupted. The bile containing conjugated bilirubin remains in the liver instead of being excreted.
More rare conditions that may cause jaundice include:
- Crigler-Najjar syndrome – an inherited condition that impairs the specific enzyme responsible for processing bilirubin, resulting in an excess of bilirubin.
- Dubin-Johnson syndrome – an inherited form of chronic jaundice that prevents conjugated bilirubin from being secreted out of the liver’s cells.
- Pseudojaundice – a harmless form of jaundice in which the yellowing of the skin results from an excess of beta-carotene, not from an excess of bilirubin; usually from eating lots of carrots, pumpkin, or melon.