REFERENCE VALUES FOR APOLIPOPROTEIN-A-I AND APOLIPOPROTEIN-B IN SERUMSTILL DEPEND ON CHOICE OF ASSAY TECHNIQUES

In a study with young children receiving growth hormone treatment, it was necessary to re-establish reference values for various blood compo nents, e. g. apolipoproteins A-I and B. We find that considerable meth od-to-method variation still exists. We used the DuPont Dimension anal yzer (D) and the Beekman Array analyzer (B) systems and a third proced ure with Orion reagents and a Kone Analyzer (K). We investigated if as say results may be pooled or exchanged within our study. In 59 serum s amples we measured apolipoprotein A-I and apolipoprotein B (n = 58) an d calculated the orthogonal regression equations y = a(S-a) x + b(S-b) . For apolipoprotein A-I the results are: (I) B = 1.165 (0.065) D - 0. 193 (0.077), S-yx = 0.055; with r = 0.922 and (II) K = 0.831 (0.056) D - 0.190 (0.066), S-yx = 0.055; with r = 0.898. For apolipoprotein B t he equations are (III) B = 1.586 (0.137) D - 0.246 (0.100), S-yx = 0.0 61; with r = 0.840 and (IV) K = 0.869 (0.065) D + 0.251 (0.048), S-yx = 0.044: with r = 0.875. According to Passing and Bablok, the slopes a nd intercept values are 1.093 and -0.126; 0.848 and 0.167; 1.500 and - 0.185; 0.880 and 0.249. The overall impression is the same for both re gression methods: comparability had not yet been achieved by early 199 3, particularly not for apolipoprotein B, and reference values differ significantly depending on the selected methodology.