Lipoprotein(a) or Lp(a) is a lipoprotein particle structurally similar to LDL, but distinctive due to the covalent linkage of apolipoprotein(a) [Apo(a)] to apolipoprotein B (a protein marker for LDL) by a disulfide bond. Apo(a) is a protein that has similarity to plasminogen, but does not have fibrinolytic activity. Recently much attention has been placed on the physiologic role of the Apo(a) portion of the Lp(a) molecule. The competition of Lp(a) with plasminogen for binding in the coagulation/fibrinolysis system and the presence of cholesterol esters with the Lp(a) particle have been studied.
The test may provide in conjunction with other lipoprotein tests, the risk assessment of coronary artery disease for specific populations.