Immunonephelometric/turbidimetric apolipoprotein B assays for the clinical laboratory

Because apolipoproteins are a part of complex macromolecular particles, modifications to the assay system may substantially alter results of immunological measurement. Accuracy as analytical recovery cannot be effectively determined by adding exogenous apolipoproteins because antibody access differs from access to endogenous apolipoproteins. Clinical studies are essential for determining accuracy in terms of clinical effectiveness. Since different kit methods use different reagent systems, the purpose of the present study was to compare total cholesterol and LDL cholesterol as markers for coronary artery disease with apo B by automated rate nephelometric, end-point nephelometric and turbidimetric kit methods. The subjects were age matched, male patients with and without angiographically documented coronary artery disease. High correlation coefficients (0.95-0.96) between the assays for both the normal and disease groups indicate that the methods are providing similar information: apo B was a better marker for coronary artery disease (CAD) than total or LDL cholesterol on the basis of univariate, multivariate and Bayesian statistics and correlated best with non-HDL cholesterol. Apo B along with HDLC could explain the variability between the CAD and normal groups without LDLC, total C, or triglycerides.