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Lipoprotein (a) [Lp(a)] is a lipoprotein which has a plasma concentration that is highly correlated with cardiovascular disease. In this study, the new Lp(a) assay for the Vitek Immuno-Diagnostic Assay System (VIDAS) developed by bioMerieux was evaluated. This method uses an enzyme linked fluorescent immunoassay (ELFIA) technique. Within-run and between-run reproducibility of the Vidass Lp(a) assay are characterized by coefficients of variation (CV) of 3 to 5.9% and 3.9 to 5.9%, respectively. Using analysis of variance, no statistical difference was shown between ELFIA and immunonephelometric assay (INA). When comparing results of the Vidas Lp(a) test with the INA, a highly significant correlation of r = 0.9708 and regression line equation y = 0.963x-0.037 was found. Interference of lipemia was studied: no influence was observed up to 12.3 mmol l(-1) triglycerides. No interference of haemoglobin was noted for Lp(a) > 0.20 g l(-1). Hyperbilirubinemia ( > 120 micromol l(-1)) led to results being underestimated for concentrations of Lp(a) which were < 0.20 g l(-1). No pre-analytical interference of citrate was measured but pre-analytical interference of EDTA was found. In conclusion, this new fully automated immunofluorimetric Lp(a) assay enables to the rapid, accurate and reliable determination of Lp(a) in blood samples.

A rapid electrophoretic method detecting serum lipoprotein(a) (Lp(a)) was described. When serum lipoproteins were electrophoresed using an agarose gel film containing 0.6% agarose and 3% sucrose, a distinct extra-band was frequently detected between beta- and prebeta-bands. This lipoprotein band was identified as Lp(a) by immunoblotting technique using anti-Lp(a) serum. Using this electrophoretic method, we studied 1353 subjects with a variety of diseases. The Lp(a)-positive subjects accounted for 8.4% of all. Neither sex nor age influenced the frequency of Lp(a) positivity. Frequencies of definite myocardial infarction in Lp(a)-positive subjects did not differ significantly from those in Lp(a)-negative ones. Those of cerebral infarction in Lp(a)-positive subjects were significantly higher than those in Lp(a)-negative ones. An electrophoretic method described herein is very useful for the rapid detection and screening of Lp(a), and hence for large-scale clinical studies of atherosclerotic risk assessment.

A lipoprotein-X (LP-X) test has been performed in normal subjects and in patients with hepatobiliary diseases and haemolytic anaemia. Statistical analysis revealed a correlation between the occurrence of LP-X and increase of conjugated bilirubin and alkaline phosphatase. The LP-X test makes it possible to differentiate obstructive from non-obstructive jaundice but it fails to demonstrate or exclude cholestasis in all cases and cannot distinguish between intrahepatic and extrahepatic cholestasis.