Bilirubin is a product of haemoglobin breakdown, which is a protein in red blood cells. It is removed from the body via the liver, stored and concentrated in the gallbladder and secreted into the bowel. In the liver, most of the bilirubin is chemically attached to another molecule before it is released in the bile. This attached bilirubin is called conjugated or direct bilirubin.
What might a high result mean?
Elevated levels of bilirubin can cause the skin and whites of eyes to become yellow (jaundice) as bilirubin builds up around the body. This is most likely caused by the liver being unable to remove sufficient bilirubin from the blood, and so an excessive amount begins to circulate around the body. This can be caused by liver damage such as cirrhosis, or an inherited disorder called Gilbert's syndrome.
Raised levels of bilirubin can also be found in individuals with a blocked bile duct, where disorders such as gallstones stop bilirubin from being excreted into the urine, causing it to build up in the blood.