Cachexia (pronounce /kəˈkɛksiə/) is loss of weight, muscle atrophy, fatigue, weakness and significant loss of appetite 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, metabolic acidosis (from decreased protein synthesis and increased protein catabolism) certain infectious diseases (e.g. tuberculosis, AIDS) and some autoimmune disorders, or addiction to drugs such as amphetamines or cocaine. Cachexia physically weakens patients to a state of immobility stemming from loss of appetite, asthenia, and anemia, and response to standard treatment is usually poor.