Bilirubin,is a breakdown product of the heme containing proteins in the body.Serum and urine bilirubin are very common laboratory test used as a component of liver function test.
Bilirubin is found in the body,in two forms - conjugated[direct] and unconjugated[indirect] bilirubin.
Conjugated bilirubin,is that bilirubin that is water soluble thus excreted by the kidney.
Unconjugated bilirubin, is water insoluble,and remains bound with albumin in the blood.
Normal total serum bilirubin concentration is less than 1mg/dl.