Quality control of biomarker measurement in epidemiology.

The throughput and complexity of a biomarker assay will determine the amount of effort that can be expended on quality control and assurance. Clinical chemistry quality control procedures can be readily applied to simpler chemical analysis such as blood lead and cholesterol, but even complex cell-based biomarker techniques such as HPRT mutation analysis and cytogenetics benefit from a formal quality control approach. Collaborative interlaboratory exercises are essential, especially when no certified reference material is available, and these can play a central role in the control of laboratory drift. Recommendations are made for the quality control of biomarker measurement based on clinical chemistry techniques. These include recommendations for coding samples so that the laboratory scientist is unaware of exposure status and for the use of formal laboratory protocols.