Claim: Certain diseases are indicated by levels of bilirubin.

Bilirubin -LRB- formerly referred to as haematoidin and discovered by Rudolf Virchow in 1847 -RRB- is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates . This catabolism is a necessary process in the body 's clearance of waste products that arise from the destruction of aged red blood cells . First the hemoglobin gets stripped of the heme molecule which thereafter passes through various processes of porphyrin catabolism , depending on the part of the body in which the breakdown occurs . For example , the molecules excreted in the urine differ from those in the feces . The production of biliverdin from heme is the first major step in the catabolic pathway , after which the enzyme biliverdin reductase performs the second step , producing bilirubin from biliverdin .   Bilirubin is excreted in bile and urine , and elevated levels may indicate certain diseases . It is responsible for the yellow color of bruises and the yellow discoloration in jaundice . Its subsequent breakdown products , such as stercobilin , cause the brown color of feces . A different breakdown product , urobilin , is the main component of the straw-yellow color in urine .   It has also been found in plants .