Nutritional assessment is an indispensable tool for the evaluation and clinical monitoring of patients with acute kidney injury (AKI). Acute loss of renal function interferes with the metabolism of all macronutrients, responsible for proinflammatory, pro-oxidative and hypercatabolic situations. The major nutritional disorders in AKI patients are hypercatabolism, hyperglycemia, and hypertriglyceridemia. Those added to the contributions of the underlying disease, complications, and the need for renal replacement therapy can interfere in the nutritional depletion of those patients. Malnutrition in AKI patients is associated with increased incidence of complications, longer hospitalization, and higher hospital mortality. However, there are few studies evaluating the nutritional status of AKI patients. Anthropometric parameters, such as body mass index, arm circumference, and thickness of skin folds, are difficult to interpret due to changes in hydration status in those patients. Biochemical parameters commonly used in clinical practice are also influenced by non-nutritional factors like loss of liver function and inflammatory status. Although there are no prospective data about the behavior of nutritional markers, some authors demonstrated associations of some parameters with clinical outcomes. The use of markers like albumin, cholesterol, prealbumin, IGF-1, subjective global assessment, and calculation of the nitrogen balance seem to be useful as screening parameters for worse prognosis and higher mortality in AKI patients. In patients with AKI on renal replacement therapy, a caloric intake of 25 to 30 kcal/kg and a minimum amount of 1.5 g/kg/day of protein is recommended to minimize protein catabolism and prevent metabolic complications.

The objective of this study was to perform a nutritional assessment of acute kidney injury patients and to identify the relationship between nutritional markers and outcomes. This was a prospective and observational study. Patients who were hospitalized at the Hospital of Botucatu School of Medicine were evaluated between January 2009 and December 2011. We evaluated a total of 133 patients with a clinical diagnosis of acute kidney injury and a clinical presentation suggestive of acute tubular necrosis. We explored the associations between clinical, laboratory and nutritional markers and in-hospital mortality. Multivariable logistic regression was used to adjust for confounding and selection bias. Non-survivor patients were older (67 ± 14 vs. 59 ± 16 years) and exhibited a higher prevalence of sepsis (57.1 vs. 21.4%) and higher Acute Tubular Necrosis-Individual Severity Scores (0.60 ± 0.22 vs. 0.41 ± 0.21) than did survivor patients. Based on the multivariable analysis, laboratorial parameters such as blood urea nitrogen and C-reactive protein were associated with a higher risk of death (OR: 1.013, p=0.0052; OR: 1.050, p=0.01, respectively), and nutritional parameters such as low calorie intake, higher levels of edema, lower resistance based on bioelectrical impedance analysis and a more negative nitrogen balance were significantly associated with a higher risk of death (OR: 0.950, p=0.01; OR: 1.138, p=0.03; OR: 0.995, p=0.03; OR: 0.934, p=0.04, respectively). In acute kidney injury patients, a nutritional assessment seems to identify nutritional markers that are associated with outcome. In this study, a low caloric intake, higher C-reactive protein levels, the presence of edema, a lower resistance measured during a bioelectrical impedance analysis and a lower nitrogen balance were significantly associated with risk of death in acute kidney injury patients.