Weight loss

Weight loss : Weight loss may be 'physiological' due to dieting, exercise, starvation, or the decreased nutritional intake which accompanies old age. Alternatively, weight loss may signify disease; a loss of more than 3 kg over 6 months is significant.
Hospital and general practice weight records may be valuable, as may reweighing patients at intervals, as sometimes weight is regained or stabilises in those with no obvious cause.

Pathological weight loss can be due to psychiatric illness, systemic disease, gastrointestinal causes or advanced disease of any specific organ system.

• Physiological' weight loss: This may be obvious in cases of young individuals who describe changes in physical activity or social circumstances. It may be more difficult to be sure in older patients when a history of nutritional intake may be unreliable.

• Psychiatric illness anorexia nervosa,bulimia and affective disorders.
• Alcoholic patients lose weight as a consequence of self-neglect and poor dietary intake.
• Systemic diseases

1. Chronic infections including tuberculosis , HIV, recurrent urinary or chest infections, and a range of parasitic and protozoan infections should be considered.
2. Weight loss is a late feature of disseminated malignancy (carcinoma, lymphoma or other haematological disorders).
3. Gastrointestinal disease Almost any disease of the gastrointestinal tract can cause weight loss.

§  Dysphagia and gastric outflow obstruction cause defective dietary intake.

§  Malignancy at any site may cause weight loss by mechanical obstruction, anorexia or cytokine-mediated systemic effects.

§  Malabsorption from pancreatic diseases or small bowel causes may lead to profound weight loss with specific nutritional deficiencies.

§  Inflammatory diseases such as Crohn's disease or ulcerative colitis cause anorexia, fear of eating and loss of protein, blood and nutrients from the gut.

4. Specific diseases of any major organ system.

Diagnosis : When weight loss is due to serious organic disease a careful history, physical examination , laboratory tests (biochemical or haematological) and  relevant imaging will usually define other features that lead to a specific diagnosis.