Trace elements, also known as trace minerals or trace metals, were a topic discussed in a research workshop during the 2009 ASPEN Clinical Nutrition Week Conference. As the name suggests, these substances are essential nutrients required in very small or “trace” amounts when compared to other TPN components such as Dextrose, Amino Acids, or Electrolytes. Although required in small amounts, trace elements are critical to proper metabolism and cell function. The widely accepted trace elements for TPN compounding include Zinc, Copper, Manganese, Chromium, and Selenium. Although available as separate additives, it is common practice to use a standard mixture containing fixed amounts of each trace element. Although this practice is not likely to be problematic in the short-term, long-term TPN users may develop excesses of some trace elements and deficiencies in others. The ASPEN research workshop speakers generally agreed it was beneficial to provide trace elements as individual additives rather than mixtures containing fixed ratios. The recommendations are tabulated below along with the contents of a standard trace element mixture:

Clinical monitoring of long-term TPN users requires not only lab tests, but evaluation of physical status. Increased gastrointestinal losses (eg. diarrhea, G or J-tube venting) may increase the loss of Zinc and Copper. Thus over the long term, it would be advantageous to increase just the Zinc and Copper in the TPN. Conversely, cholestasis (decreased bile elimination) can elevate Copper and Manganese. By providing trace elements from separate stock solutions, the Copper and Manganese could be reduced or completely removed from the TPN, while adequate amounts of the other trace elements could still be given. This flexibility does not exist if a stock trace element mixture is used. While lab monitoring is important for long-term TPN users, its usefulness is limited with regard to trace elements because blood levels are not good indicators of total body stores. This point was emphasized many times during the ASPEN research workshop. For example, a Copper level may be normal, but anemia unresponsive to conventional therapy may indicate deficiency.