Reference system for cholesterol measurements.

A reference system for cholesterol measurement is necessary to assure accuracy of cholesterol measurements by clinical, research, and manufacturers' laboratories. Such a reference system is based on the collaboration of laboratory and clinical professionals, research groups, professional societies, government groups, and manufacturers of diagnostic products. Essential components include a definitive method, a reference method, and commutable reference materials that are accurately labeled and have long-term stability. A mechanism by which clinical, research, and manufacturers' laboratories can establish traceability to the reference system is also needed. In the United States, the NRS/CHOL was organized as part of the National Reference System for the Clinical Laboratory. The major organizational components of the NRS/CHOL include the National Institute for Standards and Technology, the CDC, the CRMN, the CAP, the AAB, regional reference programs, and manufacturers of cholesterol diagnostic products. The NIST maintains an isotope dilution-mass spectrometer definitive method and distributes certified reference materials. The CDC maintains a modified Abell-Levy-Brodie-Kendall reference method and offers a CDC-NHLBI Lipid Standardization Program; the CRMN provides reference method analyses on specimens furnished by manufacturers and clinical or research laboratories; CAP, AAB, and regional reference programs provide either proficiency testing, quality assurance programs, or both; and manufacturers assure that results on diagnostic products are the same as those achieved when using fresh patient specimens and the NRS/CHOL reference method. The NRS/CHOL has contributed much to the success of clinical epidemiologic and research and development investigations in coronary heart disease.