Vitamin D, known as the sunshine vitamin, is part of a group of fat-soluble prohormones that encourage the metabolism of calcium and phosphorus in the body. Increasing research is now uncovering evidence illustrating the importance of vitamin D in protecting against a whole host of health issues. It is also estimated that as much as half the population in the world is deficient in vitamin D. The FastPack^® IP Vitamin D Immunoassay is intended for the quantitative determination of total 25-hydroxyvitamin D and other hydroxlated metabolites in human serum and plasma. This assay is designed for use with the FastPack^® IP System, which is designed specifically for use in the practice laboratory setting.