QUANTIFICATION OF LIPOPROTEIN(A) - COMPARISON OF AN AUTOMATED LATEX-ENHANCED NEPHELOMETRIC ASSAY WITH AN IMMUNOENZYMOMETRIC METHOD

Several studies indicate the relevance of lipoprotein(a) (Lp(a)) in th e genesis of premature coronary artery disease. A simple method for de termining the concentration of Lp(a) is therefore of great interest fo r assessing the risk of coronary artery disease in patients. We compar ed a new latex-enhanced immunonephelometric assay (Behringwerke AG, Ma rburg, Germany), using the Behring Nephelometer System 100, with an es tablished immunoenzymometric assay (Immune, Heidelberg, Germany). A to tal of 163 patients was studied. Intra- and inter-assay coefficients o f variation were between 2.2% and 7.1%, and between 3.4% and 8.6%, dep ending on the concentration of Lp(a). The correlation between the stud ied assays was excellent (r = 0.93, y = 0.98x -1.57, Spearman rank, Pa ssing & Bablok). When values above 1000 mg/l for Lp(a) were excluded, the correlation was even higher. Increased light scattering with parti cle size, which hitherto has been a disadvantage of the nephelometric technique, seems to be negligible using the improved latex-enhanced ap proach. In patients with triacylglycerol values above 4.5 mmol/1 (n = 19) there was no interference with the Behring system, i. e. the resul ts of the nephelometric method were not increasing, and they agreed wi th those of the immunoenzymometric assay. In conclusion, this new late x-enhanced nephelometric immunoassay represents a rapid and precise me thod for the quantification of Lp(a).