What is Lp(a)? The blood value you test once and know for life

So what is lipoprotein a? Put simply: Lp(a), also written lp(a), is the short name for lipoprotein(a). Lipoproteins are the parcels your blood uses to carry fat and cholesterol, because those two do not dissolve in blood and cannot travel through it loose. Lp(a) is one of those parcels, and it closely resembles the LDL your GP talks about. There is one difference, and that difference does everything: an Lp(a) particle has an extra protein bolted onto it, apolipoprotein(a), usually shortened to apo(a). That makes it behave worse than ordinary LDL. It can lodge in your artery wall just as LDL does, and on top of that the extra protein closely resembles the one your body uses to clear away blood clots, so it gets in the way of that clearing.

An Lp(a) blood test therefore measures how many of these particles are swimming around in your blood, in grams per litre (g/l). And now the point you are probably looking for: this particle is not measured in a standard cholesterol test. When your GP has your LDL cholesterol and your total cholesterol taken, Lp(a) does not show up there. You cannot read from those numbers whether your Lp(a) is high or low. A tidy cholesterol result therefore does not rule out a high lipoprotein a, and that is exactly why it needs a separate test of its own.

How much Lp(a) your liver produces comes down to one piece of inherited material: the LPA gene. What decides it is how often a small stretch of that gene, the KIV-2 repeat, occurs in it. Few repeats means a small apo(a) protein and a lot of Lp(a) in your blood. You inherited that from your parents, and it explains more than 90 percent of the difference between people. Your value was therefore already fixed before you made a single choice about food, exercise or weight.

Finally, glance at the unit on your result. Ours prints g/l. That is a measure of weight, as is the mg/dl you meet in foreign articles: 0.30 g/l is exactly 30 mg/dl. More confusing is nmol/l, because that counts the number of particles rather than weighing them. Since the apo(a) protein is much larger in one person than in another, the same number of particles does not weigh the same in everyone. There is therefore no reliable fixed conversion table between the two. So never set results in different units side by side as if they were one and the same measurement.

The question almost everyone on this page has: my cholesterol was fine, so why would this number tell me anything new? The answer is that your cholesterol test and your Lp(a) look at two different things. The first measures how much cholesterol is going around. Lp(a) is a separate, inherited particle that does not come along in that figure and that raises the risk of cardiovascular disease in its own right. Two people with exactly the same cholesterol profile can therefore carry a very different risk, purely because of this one number.

Genetic research shows it plainly: people who naturally produce a lot of Lp(a) more often have a heart attack or a narrowing of the coronary arteries, even when their cholesterol, their blood pressure and their lifestyle are perfectly in order. That immediately solves a puzzle many families live with. A father who never smoked, was not overweight and had a tidy cholesterol value, and yet had a heart attack at fifty. Lp(a) is often the piece missing from that story.

Risk climbs gradually with your value. There is no line below which you are safe and above which you suddenly are not. Roughly one in five people sits above the boundary that counts as raised, which makes Lp(a) one of the most common inherited risk factors there is. At very high values, the risk across a whole lifetime is comparable to that of people with inherited high cholesterol. Lp(a) is also linked not only to furring arteries but to calcification of your aortic valve. You will read that on almost no patient page, and it belongs there.

So why has your GP never had it taken? Two reasons, and neither of them is that it does not matter. It is not part of the standard cholesterol package, so it does not simply fall out of one. And for years the thinking was: what would you do with the result, there is no pill for it anyway. That last part has shifted. Not because there now is a pill, but because it has become clear that a raised Lp(a) changes how strictly the rest of your values are watched.

And that is what you do with the result. If you know you sit high, then the things you can steer weigh more heavily: the number of harmful particles in your blood, which you read from ApoB and non-HDL cholesterol, plus your blood pressure, smoking and your blood sugar. A statin, incidentally, does not help here: it lowers your LDL powerfully but leaves Lp(a) untouched and even lifts it slightly. Medicines that do bring Lp(a) down steeply are being developed, but whether that actually prevents heart attacks has not yet been shown. Promising, then, and still short of proven. Discuss a raised result with your GP: they decide with you what needs to happen in practice, and whether it is worth raising within your family.

The advice for Lp(a) is unlike that for any other blood value: have it tested at least once in your life, and after that not again. The 2022 European consensus recommends it for every adult. The reason is simple. Your value is genetically fixed and does not move afterwards, so checking it every year adds nothing. One draw and you know.

An annual check-up or a medical screening is therefore a fine moment to have this blood test added. You do not need to fast for it: a slice of bread beforehand will not change your Lp(a). There is extra reason to have it measured if heart attacks or strokes occurred at a young age in your family, if you already have cardiovascular disease yourself, or if a close relative has been found to have a raised Lp(a).

One moment is better skipped: during or shortly after a significant infection, an operation or a hospital stay. Lp(a) can read temporarily higher then. Wait a few weeks until you have recovered. Beyond that, an underactive thyroid and reduced kidney function can lift your value. If your result comes out unexpectedly high, it is worth having your TSH looked at as well.

This is how you read your Lp(a). At 0.30 g/l or lower (30 mg/dl) it is favourable and this inherited factor plays no part for you; the European consensus uses that limit to rule the risk out. Between 0.30 and 0.50 g/l you are in between, in what that same consensus calls the grey zone: it counts if you have other risk factors too. From 0.50 g/l (50 mg/dl) your value is called raised. That is the limit of the Dutch GP standard, set at the 80th percentile, so roughly one in five people sits above it. From roughly 1.80 g/l the consensus speaks of markedly raised, and you certainly want a doctor to look at that. One more thing to know about your own report: the laboratory itself applies an upper limit of 0.30 g/l, so a value of 0.35 can be flagged high on the form while national guidance puts it in the grey zone. Read these numbers as direction and not as a line you must land precisely under or over.

One more thing to weigh: the average Lp(a) value differs sharply by ancestry. People of African descent naturally have a clearly higher value than people of European or South Asian descent. The same number therefore does not carry the same weight in everyone. Let your GP place the number within your personal picture.