Standardizationof a Commercial (BoehringerMannheim Diagnostics)Enzymic Method for

lesterol Education Program recommends that cholesterol method accuracy ideally be within 3 % of the true value determined by the Abell-Kendall Reference Method, a com-ponent of the National Reference System for Cholesterol. As one of the Abell-Kendall network laboratories established to facilitate cholesterol standardization, the approach we rec-ommend for determining accuracy involves a comparison analysis on patients ’ specimens by the method in question and by the Abell-Kendall method. Use of fresh specimens precludes matrix interactions that may influence enzymic measurement. Using this approach, we assessed an enzy-mic method for cholesterol with two instruments (Boehringer Mannheim/Hitachi 717 and 737), with BMD reagent, controls, and calibrator. Fresh and frozen sera were analyzed with both instruments over three days. The AbelkKendall method was used at the Northwest Lipid Research Center on frozen aliquots of the same sera. Both instruments demonstrated good agreement with the Reference Method, as determined by linear regression; overall bias averaged less than-2 % for the Hitachi 717 and-1 % for the Hitachi 737 at 2000 mgIL-. i.e., within the accuracy recommendation.We observed a difference in bias for fresh and frozen specimens; with the Hitachi 717, fresh specimens exhibited-3 % bias at 2000 mg/L, but there was virtually no bias of determinations of frozen specimens. Measurement of blood cholesterol is one of the more common analytical procedures in the clinical laboratory, performed primarily because of the long-recognized associa-tion of high concentrations of cholesterol with increased risk of coronary artery disease. A consensus panel convened by the National Heart, Lung, and Blood Institute (NHLBI) in 1984 concluded that cholesterol is indeed a causal factor in coronary artery disease and that intervention is efficacious. The panel recommended adoption of uniform cutpoints, derived from a recent national epidemiology study, to facili-tate interpretation of cholesterol values and improvements in the laboratory measurement of cholesterol (1)