[Metabolism and clinical significance of lipoprotein Lp(a) (author's transl)].

With sensitive methods, the lipoprotein Lp(a) can be demonstrated in the serum of all human subjects, except patients with abetalipoproteinaemia. A high serum level of Lp(a) is considered as a risk factor for atherosclerotic vascular disease (coronary heart disease). The chemical and physical properties of Lp(a) are very similar to those of low density lipoproteins (LDL, Lp-B). In contrast to LDL, Lp(a) has an additional apolipoprotein, the specific Lp(a) antigen. From in vivo studies with 125I-labeled lipoproteins, the following conclusions can be drawn: 1. Lp(a) is not a metabolic product of other apolipoprotein B-containing lipoproteins. Apparently, Lp(a) is synthesized as a separate lipoprotein. 2. Lp(a) is not catabolized to other lipoproteins. Lp(a) leaves the plasma as an intact particle. 3. The fractional catabolic rate and the distribution between the intra- and extravascular compartment are similar for Lp(a) and LDL. 4. The serum level of Lp(a) is primarily determined by the synthetic rate and not by the catabolic rate.