Cachexia

Cachexia is loss of weight, muscle atrophy, fatigue, weakness and anorexia (a significant loss of appetite - not anorexia nervosa) in someone who is not actively trying to lose weight. It can be a sign of various underlying disorders; when a patient presents with cachexia, a doctor will generally consider the possibility of cancer, certain infectious diseases (e.g. tuberculosis, AIDS) and some autoimmune disorders. Cachexia physically weakens patients to a state of immobility stemming from anorexia, asthenia, and anemia, and response to standard treatment is usually poor.

Disease settings
Cachexia is often seen in end-stage cancer, and in that context is called "cancer cachexia". It was also prevalent in AIDS patients before the advent of triple-therapy for that condition; now it is seen less frequently in those countries where such treatment is available. In those patients who have Congestive Heart Failure, there is also a cachectic syndrome. Also, a cachexia co-morbidity is seen in patients that have any of the range of illnesses classified as "COPD", (Chronic obstructive pulmonary disease).

In each of these settings there is full-body wasting, which hits the skeletal muscle especially hard, resulting in muscle atrophy.

Mechanism
The exact mechanism in which these diseases cause cachexia is poorly understood, but there is probably a role for inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) -which is also nicknamed cachexin for this reason-, Interferon gamma (IFNɣ), and Interleukin 6 (IL-6), as well as the tumor secreted proteolysis inducing factor (PIF).

Related malnutrition syndromes are kwashiorkor and marasmus, although these do not always have an underlying causative illness; they are most often symptomatic of severe malnutrition.

Those suffering from the eating disorder anorexia nervosa appear to have high plasma levels of ghrelin. Ghrelin levels are also high in patients who have cancer-induced cachexia (Garcia et al 2005).