Patient weighing: standardisation and measurement.

Identification of patients with specific nutritional needs requires the use of appropriate weighing systems. The introduction of the Non-Automated Weighing Instruments Directive for equipment requiring an operator (Directive 2009/23/EC of the European Parliament) in hospitals in the UK has provided a framework for standardisation of measurement accuracy in weighing equipment. This article outlines the recommendations of the directive. Clinical areas in which weight measurements are especially relevant are identified. A summary of checks for local verification of weighing equipment and practice is provided. In addition, the importance of accurate height measurement to reduce error in derived values of body mass index is outlined.