Loss of appetite in acutely ill medical inpatients: physiological response or therapeutic target?

Abstract

Loss of appetite and ensuing weight loss is a key feature of severe illnesses. Protein-energy malnutrition (PEM) contributes significantly to the adverse outcome of these conditions. Pharmacological interventions to target appetite stimulation have little efficacy but considerable side effects. Therefore nutritional therapy appears to be the logical step to combat inadequate nutrition. However, clinical trial data demonstrating benefits are sparse and there is no current established standard algorithm for use of nutritional support in malnourished, acutely ill medical inpatients. Recent high-quality evidence from critical care demonstrating harmful effects when parenteral nutritional support is used indiscriminately has led to speculation that loss of appetite in the acute phase of illness is indeed an adaptive, protective response that improves cell recycling (autophagy) and detoxification. Outside critical care, there is an important gap in high quality clinical trial data shedding further light on these important issues. The selection, timing, and doses of nutrition should be evaluated as carefully as with any other therapeutic intervention, with the aim of maximising efficacy and minimising adverse effects and costs. In light of the current controversy, a reappraisal of how nutritional support should be used in acutely ill medical inpatients outside critical care is urgently required. The aim of this review is to discuss current pathophysiological concepts of PEM and to review the current evidence for the efficacy of nutritional support regarding patient outcomes when used in an acutely ill medical patient population outside critical care.

Thyroid function in critically ill patients

“…72 Because fasting in healthy individuals induces a similar NTIS response as that reported in patients who are critically ill, 12 decreased caloric intake during illness might greatly contribute to the development of NTIS. Fasting induces a decrease in serum thyroid hormones through a multifactorial mechanism and includes a decrease in serum leptin, and downregulation of hypothalamic, hypophysiotropic TRH neurons, contributing to persistently low concentrations of serum TSH (figure 4).…”

Detection and treatment of medical inpatients with or at-risk of malnutrition: Suggested procedures based on validated guidelines

“…Patients admitted to medical wards of hospitals, for instance after an acute exacerbation of a chronic condition, are at high risk to have or develop disease-related malnutrition (DRM) resulting from loss of appetite, poor nutritional intake, and disease-related catabolism [1,2]. If untreated, DRM ultimately leads to significant loss of lean and adipose tissues and affects the function and recovery of multiple organ systems [3].…”

Unraveling the Link between Malnutrition and Adverse Clinical Outcomes: Association of Acute and Chronic Malnutrition Measures with Blood Biomarkers from Different Pathophysiological States

“…Despite the high prevalence of malnutrition in the hospital setting, the underlying pathophysiologic mechanisms and their impact on laboratory findings are still incompletely understood [4,5] . Earlier studies in this area attribute a central role for cytokines in the pathogenesis of cachexia, particularly cancer cachexia.…”