Human Lp(a) ELISA KitLipoprotein(a) Lp(a) is an atherogenic lipoprotein particle formed by an assembly of LDL particles and apo(a) bound to apoB-100 component of LDL (1). Apo(a), the main constituent of Lp(a), has serine proteinase activity and is capable of autoproteolysis. Apo(a) has 4548 amino acids, variable sizes from 200 to 700 kDa, multiple isoforms, and structural homology with plasminogen. It competes with plasminogen for its binding site, inhibiting tissue-type plasminogen activator 1 and leading to reduced fibrinolysis. The mean Lp(a) protein level ranged from 78 to 175 g/ml depending on populations and the risk threshold is 300 g/ml. High levels of Lp(a) in the blood is a risk factor for myocardial infarction (MI), coronary heart disease (CHD), cerebrovascular disease (CVD), atherosclerosis, thrombosis, and stroke.