disorders of bilirubin excretion
From Wikipedia, the free encyclopedia. Bilirubin (formerly referred to as haematoidin) is the yellow breakdown product of normal heme catabolism, caused by the body's clearance of aged red blood cells which contain hemoglobin. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases.owever, in disorders involving hemolytic anemia, an increased number of red blood cells are broken down, causing an increase in the amount of unconjugated bilirubin in the blood. Because the unconjugated bilirubin is not water-soluble, one will not see an increase in bilirubin in the urine.