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Jaundice

Jaundice (icterus) is a yellow color in the skin caused by high levels of bilirubin in the blood. Bilirubin is a waste product of the body, caused by the break down of the oxygen carrying hemoglobin in red blood cells. It is removed from the blood by the liver, before passing into the gall bladder, and then onto the food in the small intestine to assist in digestion. Bilirubin also gives faeces its dark yellow brown appearance.

In dark skinned people, jaundice may only be seen as a yellowing of the whites of the eyes.

Jaundice may be confused with carotenaemia which is a yellowing of the soles and palms caused by excessive levels of vitamin A (carotene) in the blood, and is due to eating excessive quantities of yellow food (eg. carrots, pumpkins, paw paw) or supplements with large amounts of vitamin A.

There are numerous medical conditions that may cause jaundice.

An obstruction to the bile duct drainage from the liver to the small intestine will prevent bilirubin from escaping into the gut. It continues to build up in the liver, and overflows back into the blood from where it is deposited in the skin. The obstruction may be caused by a gall stone in the bile duct, cancer in the liver (hepatoma), secondary cancer in the liver that has spread from elsewhere (eg. breast, bowel), or a tumor in the pancreas which presses on and constricts the bile duct.

Cholecystitis is an inflammation or infection of the gall bladder, usually caused by gallstones that have formed within it. In most cases it causes pain and indigestion, but if the gall bladder becomes very swollen it may obstruct the bile duct to prevent bilirubin from leaving the liver.

Many newborn infants are jaundiced for a short time after birth. This is caused by immaturity of the liver, and the change from a primitive form of hemoglobin (fetal hemoglobin - HbF) which breaks down to form bilirubin, while a more mature form of hemoglobin is made in the spleen and bone marrow to replace it. In severe untreated cases, the high levels of bilirubin may damage the brain, so careful monitoring and treatment if bilirubin levels rise too high, is essential. The jaundice can be eased by ultraviolet light, which penetrates the child's delicate skin to destroy bilirubin. Sun will destroy bilirubin, as can be demonstrated by dog faeces, which turns white after being out in the sun for a week or so.

Cirrhosis is damage to the liver that results in its normal tissue being replaced by scar tissue. As the disease progresses the liver is unable to function successfully, and it cannot clear bilirubin out of the blood, resulting in jaundice. Cirrhosis may be caused by serious long lasting infections (e.g. hepatitis B), poisons or excessive alcohol intake over a long period.