The limited distribution of lipoprotein (a) (Lp(a)) to humans, Old World primates
and to the European hedgehog, has raised considerable interest and speculation regarding its
possible physiological role. Lp(a) has variable circulating concentrations (<0.1 – >100 mg/ml)
which are highly genetically determined in humans. These characteristics gave rise to several
theories concerning the origins and evolution of Lp(a). Lp(a) has a protective role after injury
since Lp(a) particles bind to macrophages and platelets membrane receptors, leading to fibrin
activation and injury healing. On the other hand, Lp(a) seems to be implicated in the formation
of atheromatic plaques but also in cerebrovascular events and stenosis of the aortic valve.
The main genetic factor determining plasma Lp(a) levels is the Lp(a) gene (LPA). Most Caucasian
people have normal plasma Lp(a) concentrations, but there is important distribution
variation according to race. Women seem to have increased Lp(a) levels compared with men,
while diabetes mellitus type 2 favours lower plasma Lp(a) levels. Nutrition, hormones and
several drugs may also influence circulating Lp(a) levels.