Xanthine oxidase (XO, EC 1.17.3.2 ) is present in appreciable amounts in the liver and jejunum in healthy individuals. However, in various liver disorders, XO is released into circulation. Therefore, determination of serum XO level serves as a sensitive indicator of acute liver damage such as jaundice. BioVision has developed an easy and sensitive assay to determine XO in variety of samples. In the assay, XO oxidizes xanthine to hydrogen peroxide (H?O?) which reacts stoichiometrically with OxiRed? Probe to generate color (at λ = 570 nm) and fluorescence (at Ex/Em = 535/587 nm). Since the color or fluorescence intensity is proportional to XO content, the XO activity can be accurately measured. The kit detects 1-100 mU xanthine o