Malnutrition, fatigue, frailty, vulnerability, sarcopenia and cachexia: overlap of clinical features

Malnutrition, fatigue, frailty, vulnerability, sarcopenia and cachexia all phenotypically present with the same features because they are subject to the operation of similar mechanistic factors. However, the conditions referred to above differ by which mechanism dominates the cause of the clinical condition. This review discusses the overlap and differences, which distinguish as well as unite these different conditions and allow a rationale for treatment.

In the continuum of malnutrition, cachexia, sarcopenia and frailty the recent activities focus on two areas. The first is a better understanding of the mechanisms of cachexia and sarcopenia and frailty. In particular, the differential effects of cytokines on muscle and on the hypothalamic system. The effects of inactivity promoting the loss of body mass in cachexia and sarcopenia as well as the positive effects of exercise. The second is the development of a synthesis of available literature to develop consensus documents about the definition, causes, diagnosis and treatment of cachexia, sarcopenia and frailty.

Loss of body tissues resulting in wasting is a common phenotype for several different conditions which can be caused by a combination of reduced food intake, excessive requirements, altered metabolism, sepsis, trauma, ageing and inactivity. They have been referred to loosely as malnutrition but in not all will respond to simply providing nutrients. In this review the common features and the differences as they relate to cause and response to treatment are discussed.