Urea is the final degradation product of protein and amino acid metabolism. Urea is found in blood and is excreted by the kidney as a component of urine. Besides its role as carrier of waste nitrogen, urea also plays a role in the countercurrent exchange system of the nephrons, allowing for re-absorption of water and critical ions from the excreted urine. Cayman’s Urea Fluorometric Assay provides a convenient method for detecting urea in plasma, serum, and urine. In this assay, urease catalyzes the hydrolysis of urea into carbon dioxide and ammonia. Ammonia reacts with the detector resulting in a fluorescent product. Fluorescence is analyzed with an excitation wavelength of 405-415 nm and an emission wavelength of 470-480 nm.