What could it mean if the whites of my eyes have turned yellow?

Q. Why would the whites of my eyes have turned yellow?

A. You need to see your doctor.

Doctors call yellow discoloration of the eyes jaundice. It's almost always related to elevated levels of bilirubin in the blood. This is especially true if you also have urine that is tan or brown in color.

Bilirubin is produced during the normal turnover of red blood cells. When old red blood cells die, hemoglobin is released into the bloodstream. The old hemoglobin is converted to bilirubin.

Bilirubin circulating in the blood is picked up by the liver. Then, it's processed by liver cells for delivery to the bile ducts. In a healthy person, the process keeps the blood bilirubin level less than 1.2 milligrams per deciliter.

There are many reasons for high blood bilirubin levels. These include:

• Excessive destruction of red blood cells: If many red cells break down at the same time (a problem called hemolytic anemia), this produces more bilirubin than the liver can handle.
• Liver cell abnormalities: Hepatitis from any cause can impair the liver cells' ability to release bilirubin into the bile, so it backs up into the blood stream.
• Liver enzyme deficiencies: Otherwise normal liver cells may have an enzyme defect that does not allow the normal movement of bilirubin into the bile ducts. The most common disorder is Gilbert's syndrome.
• Blocked bile duct: A blocked bile duct from a stone or tumor can raise the blood bilirubin level.
• Cirrhosis: A damaged, scarred liver cannot process bilirubin normally. It will also elevate the blood level.

Image: © MediaProduction/Getty Images