Jaundice

Jaundice or Icterus, yellowing of the skin, conjunctivae, and mucous membranes caused by excessive amounts of bile pigments in blood tissues. These pigments, normally present in blood as a result of the breakdown of hemoglobin in red blood cells, are filtered through the liver and excreted in feces (see Gallbladder). Excessive amounts of these pigments produce four types of jaundice.

In hemolytic jaundice there is increased production of bile pigment because of red blood-cell damage. This damage can be caused by antibodies created by a mismatched blood transfusion. In infants the antibodies can be caused by prenatal mismatch between the Rh factor in the infant's blood and that of the mother.

Newborns can also be jaundiced as a consequence of the condition known as hyperbilirubinemia. In these cases, there is a temporary defect in synthesis of the enzyme that breaks down bile to an excretable form.

Hepatocellular jaundice occurs when liver cells are damaged either by viruses (see Hepatitis), or by excessive intake of alcohol, and lose the ability to process pigment.

Obstructive jaundice follows physical obstruction of the ducts that transport pigment from the liver to the intestine. Blockage can be due to gallstones, tumor, or inflammation.