If you've ever had a bruise, you may have noticed that the damaged red blood cells in the skin went through a series of color changes as the skin healed. When you saw yellow in the bruise, you were seeing bilirubin.
Most of the time, about one percent of our red blood cells retire every day, to be replaced by the same number of fresh, young red blood cells. The old ones are processed in the liver as they are disposed of. Much of the resulting bilirubin leaves the body in the stool.
If there are too many red blood cells retiring for the liver to handle, yellow pigment builds up in the body. When there is enough to be visible, jaundice results.
The jaundice can be caused by too many red blood cells retiring, by the liver being overloaded or damaged, or by the inability to move processed bilirubin from the liver through the biliary tract to the gut.
Most babies have some jaundice during the first week of life. The ordeal of birth can send many red blood cells to an early retirement (especially if a vacuum is used!), and babies' livers are often unprepared for the load. Before Mom's milk comes in and stooling begins in earnest, bilirubin accumulates more easily. Jaundice is even more common in premature babies.
Physiologic jaundice is the name for normal jaundice commonly seen in healthy babies.
Pathologic jaundice is the name given when the jaundice presents a health risk, either because of its degree or its cause. Pathologic jaundice arises for many reasons, including blood incompatibilities, blood diseases, genetic syndromes, hepatits, cirrhosis, other liver diseases, infections, or medications. In addition, it applies to physiologic jaundice exaggerated by dehydration, prematurity, difficult delivery, or other reason.
Another condition called Gilbert's syndrome is a benign, hereditary condition in which mild jaundice develops. It is caused by low levels of some bilirubin-processing enzymes in the liver. This condition, once recognized, requires no further treatment or evaluation. There are other more rare hereditary causes of elevated bilirubin levels.
A yellow-to-orange color may be imparted to the skin by consuming too much beta carotene, the orange pigment seen in carrots. In this condition, the whites of the eyes remain white, while people with true jaundice often have a yellowish tinge to the eyes.
This condition is called hypercarotenemia or just carotenemia.
