EFFECT OF HYPERTRIGLYCERIDEMIA ON LIPOPROTEIN (A) SERUM CONCENTRATIONS

Numerous studies have shown lipoprotein (a) [Lp(a)] serum levels above 0.3 g L(-1) to be a genetically determined and independent risk facto r for atherosclerotic vascular disease. In this study of sera from 100 9 patients attending our lipid clinics, multivariate regression analys is revealed an inverse correlation between the serum concentrations of triglycerides (TG) and Lp(a) (r = -0.31; P < 0.001) as determined by electroimmunodiffusion. This was not observed in 1237 controls from a random population. Detailed analysis of the frequency distribution of Lp(a) levels at different degrees of hypertriglyceridaemia (HTG) revea led a decreasing dosage effect of HTG on Lp(a) serum levels. In 60% of patients with TG > 9.12 mmol L(-1), this effect led to undetectable s erum Lp(a) levels. Dilution of hypertriglyceridaemic samples with norm otriglyceridaemic sera containing high levels of Lp(a) revealed that a nalytical interference in part accounts for the decreasing effect of T G-rich lipoproteins on Lp(a). Re-evaluation of 45 hypertriglyceridaemi c samples by enzyme immunoassay and immunoblotting revealed the presen ce of small amounts of Lp(a) in several samples which were considered to be free of Lp(a) upon electroimmunodiffusion. We conclude that TG-r ich lipoproteins interfere with the quantification of Lp(a), at least by electroimmunodiffusion. However, HTG may also decrease Lp(a) plasma concentrations in vivo, possibly by increased clearance of TG-rich Lp (a).