Micronutrients in the severely-injured patient.

The trace element and vitamin requirements of severely-ill injured patients depend on a complex interaction of the status of the patient at the time of admission, ongoing losses and the potential benefit of supplying large amounts of individual micronutrients. Characteristic clinical deficiency states are now uncommon, but subclinical deficiency is of growing concern. The main effects of subclinical deficiency are: (1) an altered balance of reactive oxygen species and antioxidants, leading to oxidative damage of polyunsaturated fatty acids and nucleic acids, and possibly to increased activation of the transcription factor nuclear factor-kappaB, with increased production of pro-inflammatory cytokines: (2) impaired immune function with increased likelihood of infectious complications. Laboratory tests to optimize intake in such critically-ill patients lack sensitivity and specificity, this situation being made worse as a result of the acute-phase response. Recent studies have indicated the clinical benefit of providing large amounts of certain micronutrients in burned and head-injured patients. Further clinical studies are now required to define optimal levels of provision in different disease states, with a particular emphasis on markers of tissue function and clinical outcome.