• A bile pigment that is a degradation product of HEME.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• A dark orange, yellow pigment that is the product of the breakdown of iron in the blood; it is conjugated in the liver and excreted in the bile.
  NCI
  U.S. National Cancer Institute, 2021
• Bile pigment that is a degradation product of heme.
  CRISP Thesaurus
  National Institutes of Health, 2006
• Substance formed when red blood cells are broken down. Bilirubin is part of the bile, which is made in the liver and is stored in the gallbladder. The abnormal buildup of bilirubin causes jaundice.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• Bilirubin is a tetrapyrrole and a breakdown product of heme catabolism. Most bilirubin (70%-90%) is derived from hemoglobin degradation and, to a lesser extent, from other hemo proteins.
  Medscape
  WebMD, 2025
• Bilirubin, a brownish yellow pigment of bile, secreted by the liver in vertebrates, which gives to solid waste products (feces) their characteristic colour. It is produced in bone marrow cells and in the liver as the end product of red-blood-cell (hemoglobin) breakdown. The amount of bilirubin...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2025