Nutritional assessment: its role in the provision of nutritional support.

Generalised undernutrition is common in hospital patients and in the community. It is frequently unrecognised and is associated with a range of adverse consequences that contribute to increased morbidity and mortality. The National Institute for Health and Clinical Excellence recommends that all individuals engaging with healthcare or admitted to residential homes in the community should be screened for undernutrition. Laboratory investigations have little place in the diagnosis of undernutrition: this is primarily a clinical process. In particular, the measurement of serum albumin concentration, though widely promulgated in the past as an index of nutritional status, is worthless for this purpose. Laboratory investigations are, however, of importance: to diagnose specific nutritional deficiencies (eg, of trace elements) and to monitor the provision of nutritional support, to detect metabolic complications and to assess its adequacy (for which the measurement of serum prealbumin concentrations, particularly in conjunction with measurements of C-reactive protein, may be of value).