July 2, 2002

Larry H. Bernstein, MD

There is an opportunity and a necessity for the laboratory to participate in the nutritional support process in the same way that we are involved in clinical pharmacology. Laboratory services touch almost every patient, largely because of the dependence on blood gases, electrolytes, hematological and other tests to monitor patients’ status at a given time in inpatient or outpatient treatment. We have to clarify the pathophysiology of acute and chronic illness to appreciate the role of the laboratory in supporting nutritional services. We first make a distinction between malnutrition and stress hypermetabolism. Malnutrition is a hypometabolic state which results from starvation and associated downregulation of metabolic processes. It is not a metabolically-driven process. Stress hypermetabolism is a programmed upregulation of metabolic processes as a result of major injury to provide the nutrients for wound healing and to maintain immunocompetence. It is associated with considerable loss of lean body mass, which is associated with nitrogen death if the loss exceeds 40 percent. The extent of this response is proportion to the extent of the injury. Failure to appreciate this distinction results in a lack of understanding of a most important issue concerning the acutely ill patient – metabolic management.

The issues addressed are not limited to the serious problems of acute stress injury, but extend to problems of aging, disordered metabolism, and chronic disease states. Alcoholism, nonalcoholic fatty liver disease, and Type 2 diabetes have commonalities with lipid abnormalities and insulin resistance. The mechanism of these changes is also driven by upregulated metabolic processes. The increased independent risk associated with high sensitivity C-reactive protein (hCRP) may be downregulated by the use of statin drugs independently of the lipid management effect. The wasting syndromes of HIV, and to a lesser extent, COPD, CRF, Crohn’s disease, and chronic inflammatory states may associated with protein and essential fatty acid imbalance. The program calls attention to the disordered metabolism associated with all these states, and the opportunities for the laboratory in monitoring their management. The laboratory even has opportunities for monitoring the “self management” revolution introduced by the emerging “nutraceutical” market.