Physiological Variation in Laboratory Animals and Humans

Metabolites are the products and byproducts of the many complex biosynthesis and catabolism pathways that exist in humans and other living systems. Measurement of metabolites in human biofluids has often been used for the diagnosis of a number of genetic conditions, diseases, and for assessingexposure to xenobiotics. Traditional analytical approaches have been limited in scope, in that emphasis was usually placed on changes in the level of one or a few metabolites. For example, urinary creatinine and blood urea nitrogen are commonly used as parameters of renal function.