We review the general functions leading to interactions between micronutrients and other constituents that can affect their bioavailability in parenteral nutrition (PN) admixtures, assess micronutrient status of PN patients at risk of deficiencies or toxicities by laboratory testing, clinical signs, and symptoms, emphasize the importance of vigilance regarding potential chemical and physical incompatibilities in PN admixtures, and highlight the need for manufacturers and pharmacists to carefully monitor and minimize levels of trace element contamination in all PN products.