Comparison of methods for the measurement of apoproteins A1 and B in serum

We evaluated four currently available commercial methods for measuring the concentration of apoproteins A1 and B in human serum (a radioimmunoassay, an immunonephelometric assay, and two electroimmunoassays). We found that the immunonephelometric assay provided the best between-run precision, whereas the two electroimmunoassays gave the poorest. Only the immunoephelometric assay achieved a between-run coefficient of variation of less than 5%, which we believe is a desirable target for this parameter. Comparison with other laboratories was assessed using a reference serum obtained from the Centers for Disease Control, Atlanta, Georgia, USA; we are currently using this as a reference serum employing a range of +/- 15% of its assigned values as acceptable. Linearity of the immunonephelometric assay was satisfactory throughout the ranges of 0.5-2.0 g/L for apoprotein A1, and 0.3-1.8 g/L for apoprotein B.