The yellow color of urine is because of urobilin, the end product of bilirubin catabolism. One part of bilirubin is excreted by GI tract, where it gives the brown colour - stereobilin. The other part is excreted by the kidneys and the urogenital system, it gives the yellow colour - urobilin.
kovadomen t1_j9qyzvq wrote
Reply to comment by Bad_DNA in Why is urine yellow? by nateblackmt
The yellow color of urine is because of urobilin, the end product of bilirubin catabolism. One part of bilirubin is excreted by GI tract, where it gives the brown colour - stereobilin. The other part is excreted by the kidneys and the urogenital system, it gives the yellow colour - urobilin.