Lp(a)

Most of the cardiovascular markers worth tracking are ones you can change. This one is different. Lp(a) is largely written into your genes, set near birth, and stable for the rest of your life, and for about one in five people it sits high enough to roughly double their lifetime risk of heart attack, stroke, and aortic valve disease.

The strange part is how invisible it stays. A standard lipid panel does not measure it. You can have flawless cholesterol, a clean checkup, and no warning at all while carrying one of the most powerful inherited cardiovascular risk factors known, simply because nobody ordered the test.

That makes Lp(a) unusual in two ways at once. It is among the most important numbers you can know, and it is among the least likely to be measured. And because it barely moves over a lifetime, you generally only need to check it a single time.

Knowing it does not let you lower it. What it does is far more useful than that: it tells you how hard you need to work on everything else.

An Lp(a) particle is an LDL particle, complete with its single apolipoprotein B, with one additional protein bound to it: apolipoprotein(a). That extra protein is what makes Lp(a) its own creature. Structurally it is closely related to plasminogen, the precursor of the enzyme that breaks down blood clots, and that resemblance gives Lp(a) a pro-thrombotic streak, interfering with normal clot breakdown on top of its cholesterol-depositing, inflammatory effects ^[1].

Your concentration is governed almost entirely by the LPA gene, specifically by how many repeating segments it contains. Fewer repeats produce a smaller protein and, as it happens, much higher Lp(a) levels in the blood. This is why levels are roughly 90% heritable, largely fixed from early childhood, and essentially unmoved by diet, exercise, weight loss, or the lifestyle changes that lower other lipids ^[2].

What it lacks in modifiability it makes up in potency. Particle for particle, Lp(a) is roughly six to seven times more atherogenic than ordinary LDL, both because of the inflammatory oxidized phospholipids it carries and because of its clot-promoting tail ^[3]. A relatively small number of these particles can carry an outsized amount of risk.

Genetic studies settle the question of whether Lp(a) merely marks risk or causes it. People who inherit lifelong higher levels have proportionally higher rates of heart attack and aortic stenosis, the hallmark of a causal factor rather than a bystander ^[1]. This is why it is worth knowing even though you cannot change it: the risk is real, lifelong, and additive on top of everything else.

For interpretation, the molar unit, nanomoles per liter, is preferred over the older mass unit of milligrams per deciliter, because Lp(a) particles vary so much in size that a mass measurement can mislead. A common reading is that levels below about 75 nmol/L are desirable, while levels above roughly 125 carry clearly elevated risk, with the danger rising further from there ^[2]. Because the number is genetically stable, a single measurement in adulthood usually tells you what you need to know for life.

The practical consequence is a shift in strategy rather than a lever to pull. Lifestyle does not meaningfully lower Lp(a), and while targeted therapies are now in active development, none is yet a routine treatment ^[4]. What a high Lp(a) changes is the urgency of everything you can control, and the case for testing the relatives who share your genes.