Bilirubin - new insights into an old molecule.

For decades, bilirubin was thought to be merely a degradation product of the hem, a potentially toxic compound and a molecule with no specific physiological function. Recently, it has been discovered that bilirubin has a strong antioxidant effect and possesses molecular signalling, hormonal and immunomodulatory properties. Numerous studies show that moderately elevated serum bilirubin concentrations correlate with a lower risk of developing pathological conditions mediated by oxidative stress and inflammation. Low concentrations within the current reference interval have been shown to be a potential risk factor for various pathological conditions. It is to be expected that knowledge about bilirubin will lead to the determination of bilirubin concentration gaining new importance in diagnostics, for example as a prognostic marker, but also as a therapeutic molecule.