COMPARISON OF A NEW IMMUNOTURBIDOMETRIC ASSAY OF HUMAN SERUM LIPOPROTEIN(A) TO THE ELISA AND THE IRMA METHODS

In the present work we have tested a new immunoturbidometric (IT) lipo protein(a) (Lp(a)) assay and compared it with two other Lp(a) assay sy stems (IRMA and ELISA) commonly used in clinical chemistry laboratorie s. In addition, we have examined the effects of long-term storage and plasminogen on the results of Lp(a). Intra-assay and inter-assay coeff icients of variation of the IT method were from 1.6 to 5.5% and from 2 .8 to 10.7% depending on the concentration of Lp(a). The correlations between methods were 0.957 (IRMA vs. IT), 0.969 (IRMA vs. ELISA) and 0 .956 (IT vs. ELISA) and the regression curves were IRMA = 1.07IT+11, IRMA = 1.84ELISA+2 and IT = 1.62*ELISA+17, respectively. Storage of t he samples for 5 years at -70 degrees C did not affect serum Lp(a) lev els. There was a slight increasing effect of high concentrations of pl asminogen on the Lp(a) results, but on physiological serum levels of p lasminogen the effect was not significant. We conclude that the IT met hod provides a simple way to screen serum Lp(a) levels.