Trace element metabolism in parenteral and enteral nutrition.

With more patients receiving artificial nutrition, i.e., TPN and EN, deficiencies of essential trace elements have appeared. Because symptomatic deficiencies might be only a small part of the abnormalities, we should recognize a much wider background of abnormal metabolism and physiology of such elements and examine their possible participation in most diseases. Measurements of biochemical indices of trace elements in these patients frequently reveal decreased levels. To prevent marginal deficiencies and maintain good balance in the body, routine administration of trace elements is therefore essential. Discussions focus on daily requirements, including the recommended doses of each trace element in PN and EN formulas. The range of different recommended doses in different countries, and the content and completeness of trace element mixtures available in these countries is a matter of concern. A consensus based on better data from patients with different clinical states is urgently required.