The status of methods of calibration in hematology.

Three years ago, the authors described methods for calibration and quality control of Coulter automated hematology instruments. These and other methods have received fairly widespread use in hematology laboratories. The effectiveness of such use was tested through special questionnaires conducted by the College of American Pathologists in 1978. Current information indicates no clear-cut advantages between fresh whole blood and preserved-cell control materials when properly used for calibration or quality control procedures. Minor but troublesome differences persistently appear between manual or semiautomated methods and in results on fully automated systems. Likewise, daily internal quality control may be monitored by preserved cells or by continuous process control using patient samples. The various systems for calibration and quality control have certain advantages and disadvantages.