[What should be done in weight loss of unknown origin?]

Involuntary weight loss is associated with increased mortality and morbidity. Differential diagnosis includes more than 50 disease entities; therefore the diagnostic strategy is determined by additional symptoms. THE SYNDROME OF "CONSUMPTION", i.e. weight loss as an isolated symptom or together with malaise, may indicate tumors (lung, pancreas, kidney cancer, malignant lymphoma), infections (tuberculosis, HIV), immunologic diseases (lupus erythematosus, vasculitis), hyperthyroidism, extraintestinal Crohn's disease, or psychogenic disease (depression, psychogenic eating disorders).

Recognition of the underlying disease is often delayed by a lack of awareness for weight changes, both by physicians and by patients. Nutritional counselling and treatment should be initiated in time.