What Is a Lipoprotein(a) Test?

Lipoprotein(a) — written as Lp(a) and pronounced "LP little a" — is a lipoprotein particle that is increasingly recognized as one of the most important and most underappreciated cardiovascular risk factors. It is genetically determined, largely unresponsive to lifestyle changes or most conventional medications, and present at high levels in approximately 20% of the population. Despite its significance, Lp(a) testing remains dramatically underutilized — most cardiovascular patients have never had their Lp(a) measured. Understanding what Lp(a) is, why it matters, and what can be done about it is becoming essential in cardiovascular prevention.

WHAT IS LIPOPROTEIN(a)?

Lp(a) is a modified form of LDL — structurally similar to LDL, with a cholesterol-rich core surrounded by ApoB-100, but with an additional protein called apolipoprotein(a) — or apo(a) — covalently attached to the ApoB. This extra protein fundamentally changes the behavior of the particle.

Apo(a) is produced in the liver and is structurally similar to plasminogen — a blood protein involved in breaking down blood clots. Because of this structural similarity, Lp(a) may interfere with normal fibrinolysis (clot breakdown), giving Lp(a) both atherogenic (plaque-promoting) and thrombogenic (clot-promoting) properties — a particularly dangerous combination.