REFERENCE INTERVALS FOR PLASMA APOLIPOPROTEIN-B DETERMINED WITH A STANDARDIZED COMMERCIAL IMMUNOTURBIDIMETRIC ASSAY - RESULTS FROM THE FRAMINGHAM OFFSPRING STUDY

We evaluated a commercially available, standardized immunoturbidimetri c assay for apolipoprotein (ape) B, the protein constituent of low-den sity lipoprotein (LDL), to establish reference ranges for men and wome n, and to determine the concentrations associated with increased risk of coronary heart disease (CHD). The between-run CV for assay of a nor mal-concentration control for this assay was 6.60%. The mean (+/- SD) apo B concentration was 1.03 +/- 0.24 g/L in 1880 men, significantly h igher than the mean for 1944 women (0.96 +/- 0.26 g/L) participating i n cycle 4 of the Framingham Offspring Study (P <0.001). An apo B value of 1.20 g/L corresponded roughly to the 75th percentile in men, simil ar to an LDL cholesterol concentration of 1.60 g/L, and subjects with concentrations greater than this were significantly more likely to hav e CHD than subjects with apo B concentrations less than 1.00 g/L, the approximate 50th percentile (P <0.05 in men and P <0.001 in women).