Quality control in planning and operating the laboratory component for the Third National Health and Nutrition Examination Survey.

Successfully acquiring high-quality laboratory data for a long-term nutrition survey such as the Third National Health and Nutrition Examination Survey (NHANES III) requires rigorous quality-control procedures throughout the entire design and implementation of the laboratory component. We discuss selection of nutritional biochemistry analyses, proper specimen collection, and the critical need for continuity of protocol during the entire survey. The NHANES III laboratory procedures are described, including specimen collection, processing, shipment to laboratories, and analyses.