It is an indication of damage or disease to the liver. It can also indicate a destruction of red blood cells. A friend of mine was tested and treated at Mayo Clinic for this. If it is serious enough and passes through your stool this can be a possibility.
This could be described as jaundice. It causes the patients to have a change of color in pigmentation and is a form of liver disease. It is not fatal if treated properly. For more details, check http://en.wikipedia.org/wiki/Jaundice.