rezumat

A micronutrient is defined as a substance, provided by food, needed only in small amounts for normal body  function. The micronutrients can be vitamins, metals, aminoacids or more complex compounds. The paradigm behind micronutrients supplementation in critically ill patients is based on the expected modulation of the immune inflammatory response to “danger” signals that include but are not limited to infection. Micronutrients are the substrates that could modulate specific biochemical pathways that are dysfunctional (mainly depleted) because of excessive consumption during the critical illness. Although this paradigm is conceptually interesting, there are many unanswered questions concerning micronutrient supplementation for critically ill patients. The goals of the present article are: (i) to propose definitions for micronutrients; (ii) to list the many questions that have been or must be asked concerning micronutrients; (iii) specifically review two micronutrients (vitamin A and iron); (iv) attempt to provide clinical insight, when possible, for these two micronutrients. Despite efforts to understand micronutrient biology and pharmacology, there are still many unasked and unanswered questions. Medical action, for the moment, is recommended based on a limited number of studies which are considered to be of poor methodological quality. For the two micronutriments that were specifically discussed in this article, the conclusion is that vitamin A supplementation is not recommended in critically ill patients. For iron supplementation, weak recommendations are published for specific groups of patients. Furthermore, all clinicians should be familiar with the limitations of laboratory tests that can be used to assess iron status.