ISRNM PROCEEDINGS Nutritional Evaluation and Management of AKI Patients Enrico Fiaccadori, MD, PhD,* Umberto Maggiore, MD, PhD,* Aderville Cabassi, MD,* Santo Morabito, MD,† Giuseppe Castellano, MD,‡ and Giuseppe Regolisti, MD* Protein-energy wasting is common in patients with acute kidney injury (AKI) and represents a major negative prognostic factor. Nutri- tional support as parenteral and/or enteral nutrition is frequently needed because the early phases of this are often a highly catabolic state, although the optimal nutritional requirements and nutrient intake composition remain a partially unresolved issue. Nutrient needs of patients with AKI are highly heterogeneous, depending on different pathogenetic mechanisms, catabolic rate, acute and chronic co- morbidities, and renal replacement therapy (RRT) modalities. Thus, quantitative and qualitative aspects of nutrient intake should be fre- quently evaluated in this clinical setting to achieve better individualization of nutritional support, to integrate nutritional support with RRT, and to avoid under- and overfeeding. Moreover, AKI is now considered a kidney-centered inflammatory syndrome; indeed, recent ex- perimental data indicate that specific nutrients with anti-inflammatory effects could play an important role in the prevention of renal func- tion loss after an episode of AKI. Ó 2013 by the National Kidney Foundation, Inc. All rights reserved. Introduction A CUTE KIDNEY INJURY (AKI), usually as a part of multiple organ system failure syndrome, is an impor- tant therapeutic challenge in critically ill patients, in whom its incidence rate can be as high as 25% to 40%, with mor- tality rates reaching 50% of patients. 1 Renal replacement therapy (RRT) is often needed and is performed by contin- uous or prolonged intermittent, highly efficient modali- ties 1,2 with possible effects on nutrient balance. The aims of nutritional support in these patients should be to reduce the negative effect of critical illness on lean body mass and preserve the internal milieu. The peculiar metabolic derangements of the acutely uremic state, as well as the effects of specific RRT modalities on macro- and micronutrient needs and balances, should be carefully evaluated to integrate nutritional support and RRT. Lean body mass wasting and fat mass depletion occurring in AKI are now defined as ‘‘protein-energy wasting’’ (PEW). 3 However, the low sensitivity/specificity of the currently available nutritional parameters and the difficult identification of critically ill patients at increased risk for PEW still represent major problems in the nutritional eval- uation of patients with AKI. 4 Up to 40% of these patients have PEW, which represents a negative prognostic factor in terms of increased length of hospital stay, complication rate, and mortality risk. 5 The possible advantages of nutritional support on nutri- tional status, morbidity, and mortality remain unproven, al- though some observational data suggest a correlation between positive nitrogen balance and better outcomes in critically ill patients with AKI requiring continuous RRT. 4 Pathogenesis of PEW in AKI Many factors and mechanisms participate in the complex pathogenesis of PEW in patients with AKI 4 ; a key role is played by the altered status associated with the acute loss of kidney homeostatic function, insulin resistance, inflam- mation, and oxidative stress. 4 In fact, AKI is now viewed as the consequence of an inflammatory process spreading from the kidney to the other organ systems, 6 and metabolic alterations are considered part of the systemic effects of a ‘‘kidney-centered’’ inflammatory syndrome. Goals of Nutrient Intakes in AKI Measured energy expenditure in AKI rarely exceeds 1.3 times the basal energy expenditure calculated by the Harris- Benedict equation and is on average 27 kcal/kg per day in critically ill patients with AKI. 7 Because actual body weight in AKI is highly influenced by water balance, the calculated energy requirements should be based on usual or ideal body weight. Protein catabolic rate values are 1.4 to 1.8 g/kg per day in patients with AKI on RRT 6-8 ; thus, at least 1.5 g of protein per kilogram of body weight per day are usually required to achieve less negative or nearly positive * Renal Failure Unit, Department of Clinical and Experimental Medicine, Parma University Hospital, Parma, Italy. † Nephrology and Dialysis, University Hospital Umberto I University of Rome La Sapienza, Rome, Italy. ‡ Nephrology Dialysis and Transplant Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy. Financial Disclosure: The authors declare that they have no relevant financial interests. Address correspondence to Enrico Fiaccadori, MD, PhD, Universita’ degli Studi di Parma, Via Gramsci 14, 43100 Parma, Italy. E-mail: enrico. fiaccadori@unipr.it Ó 2013 by the National Kidney Foundation, Inc. All rights reserved. 1051-2276/$36.00 http://dx.doi.org/10.1053/j.jrn.2013.01.025 Journal of Renal Nutrition, Vol 23, No 3 (May), 2013: pp 255-258 255