Table 2.

Some definitions of “malnutrition” in dialysis patients.

Definitions	Advantages	Limits
Malnutrition	Intuitive and comprehensive; replaces the obsolete term “denutrition”, highlighting the importance not only of quantity of food but also of its distribution and quality.	The definition has changed over time, and the term is usually employed to describe a combination of muscle wasting, low nutrient intake, and low nutritional markers. Its meaning in the context of “poor quality nutrition” is often lost. Generic, too often based on albumin levels, now recognized as only one of the markers of malnutrition in dialysis patients (interference with mode of dialysis and inflammation). Focuses attention on intake, and less on causes of wasting (see below)
Wasting	Proposed in 1983 by the World Health Organization to define an involuntary loss of weight of more than 10% in absence of specific diseases such as opportunistic infection, cancer, or chronic diarrhea.	Generic, the time of development is not univocally defined. Probably more able to describe rapid changes, which are not the most frequent in dialysis patients, in which the process is often long. Focuses attention on intake, which may be the result and not the cause of an underlying process.
PEW: Protein-Energy Wasting	Widely used. proposed by the International Society of Renal Nutrition and Metabolism. Focuses attention on the relationship between malnutrition and metabolic background.	Often only considers albumin and cholesterol; may be biased in hyperlipidemia patients and does not account for the causes of low albumin levels. Includes BMI, but obese sarcopenia may be overlooked.
MIA: Malnutrition Inflammation Atherosclerosis syndrome	Focuses attention on the relationship between malnutrition, inflammation, and comorbidity. It is a dynamic index and is sensitive to variations in clinical status.	Relies, among other indexes, on subjective evaluations, which may be operator-dependent. Includes BMI, but obese sarcopenia may be overlooked.
Cachexia	According to the Society on Sarcopenia, Cachexia and Wasting Disorders (2008), cachexia is a complex metabolic syndrome associated with underlying illness and characterized by loss of muscle, with or without loss of fat. According to the International Society of Renal Nutrition and Metabolism (2008), cachexia is the last stage of PEW.	The different definitions make systematic use of this term difficult. The Society on Sarcopenia, Cachexia and Wasting Disorders has introduced the concept of fatigue, which may be misleading in severe chronic diseases and in elderly patients.