Bilirubin is light-sensitive. Therefore, urine specimens should be protected from excessive light exposure and examined as soon as possible after specimen collection. On standing, bilirubin, which has a goldish color, is oxidized to biliverdin, which is a green color. Many of the procedures used to detect bilirubin will not react with biliverdin, so false-negative results may occur if urine is not fresh when tested.
