Lipoprotein(a): what it is, what it tells you and why we test it

Lipoprotein(a) is a particle that carries cholesterol, like LDL, with an extra protein attached. Its level is set almost entirely by your genes and stays much the same for life. If it is high, it raises the risk of heart attack and stroke, even with a normal LDL.

Why we test it

Like LDL, it carries cholesterol that can build up in the walls of your arteries and narrow them over time.

If it is high, it raises the risk of heart attack, stroke and a narrowing of the aortic valve, the valve that lets blood out of the heart. This happens even with a normal LDL.

A high lipoprotein(a) is common: worldwide it affects about 1.4 billion people. But a standard check-up usually leaves it out, so many people do not know theirs is high.

What it tells you, and what it does not

It tells you whether you have inherited an extra risk for your heart and arteries. It can explain why heart attacks or strokes at a young age run in a family, even when cholesterol looks fine.

It does not tell you whether you have heart disease. It is one risk factor, read together with the others: LDL, blood pressure, glucose and smoking.

If it is low, there is nothing to do.

That is why it is read together with other tests:

• LDL cholesterol: The cholesterol you can lower the most
• ApoB: How many particles can build up in your arteries
• High-sensitivity CRP: Whether there is inflammation, which can raise it for a while
• HDL cholesterol: Part of the calculation of your heart risk

Normal lipoprotein(a) levels

The lab decides what is normal. A value below 75 nmol/L is usually considered normal. Your own report may print different limits.

Many lab reports give it in mg/dL. There is no exact conversion, because it depends on the size of the particle, which varies from person to person. As a guide: 75 nmol/L is about 30 mg/dL, 125 about 50 and 430 about 180.

Below 75 nmol/L the risk that comes from lipoprotein(a) is low. Between 75 and 125 is a grey zone, read together with everything else. From 125 up the risk rises.

In the Rosa report you also see your optimal range, with lipoprotein(a) read together with LDL and ApoB.

What your result means

Find the row for your result: the table is in nmol/L. If your report uses mg/dL, the numbers are lower: 30 mg/dL is about 75 nmol/L, 50 about 125 and 180 about 430. From 430 nmol/L up it should always be seen by a doctor.

• Below 75: Normal. The risk that comes from lipoprotein(a) is low. You usually do not need to test it again. In the Rosa report you also see whether you are in your optimal range.
• 75 to under 125: Slightly high. It is a grey zone: it matters most if you have other risk factors. Keep your LDL, blood pressure and glucose low, and do not smoke.
• 125 to under 430: High. It raises the risk of heart attack and stroke, even with a normal LDL. Talk to your doctor and keep your other risk factors low. Tell your close relatives.
• 430 and above: Very high. Your lifetime heart risk is much higher than average, but it can be brought down. Talk to a doctor, and have your close relatives tested too.

If your lipoprotein(a) is high

• High lipoprotein(a): It is usually inherited and causes no symptoms. The number barely moves, but your risk comes down when you keep the other risk factors low.

Why lipoprotein(a) is high

Almost always because of your genes. The other causes are rarer.

• Your genes: By far the most common cause. The level is inherited from your parents and changes little in adult life.
• Kidney disease: Some kidney diseases push it up, sometimes a lot.
• Menopause: In women it tends to rise a little at menopause.
• A slow thyroid: When the thyroid works too little it can rise. It comes down a little with treatment.

Why one test is enough

Your genes set the level, and in adult life it changes little. Diet, exercise and weight loss barely move it.

That is why one test in a lifetime is usually enough, ideally with your first cholesterol check.

It is repeated only in a few cases: kidney or liver disease, an infection at the time of the blood test, or a first test taken before menopause.

High lipoprotein(a): what to do

The number barely changes, but your overall risk can come down. Where to start:

• Keep your LDL low: with a high lipoprotein(a), doctors usually aim for a lower LDL.
• Keep your blood pressure and glucose in check.
• Do not smoke, move every day and keep a healthy weight.
• If you take cholesterol medicines, do not stop them: the most common ones do not lower lipoprotein(a), but they lower LDL, and that counts.
• Tell your close relatives: parents, brothers, sisters and children may have it high too, and one blood test tells them.

In studies, among people with a high lipoprotein(a), those with healthy habits and numbers had about a third of the risk of those without them.

What can skew the result

The number barely moves. Only a few things change it, and it helps to know them before you read it.

• An infection or inflammation: During an acute illness it can read higher than usual. Best to test it once you have recovered.
• Hormone therapy: Hormone therapy for menopause lowers it a little. If you take it, tell your doctor.
• Pregnancy: In pregnancy it can double. Best to test it at another time.
• Eating before the test: It does not change it: lipoprotein(a) needs no fasting. Other tests in the same draw usually do, though.

When to worry

Talk to a doctor if:

• Your lipoprotein(a) is 430 nmol/L or more, about 180 mg/dL.
• It is 125 nmol/L or more, about 50 mg/dL, and heart disease, stroke, high blood pressure, high cholesterol or high triglycerides run in your family.
• It is high and you have other risk factors too: high LDL, high blood pressure, diabetes or smoking.
• You have chest pain or pressure: call 112 straight away.
• You get short of breath with effort more than usual: see a doctor soon.

With Rosa, a lipoprotein(a) of 430 nmol/L or more is always flagged to a doctor. From 125 up, it is flagged if your profile lists heart disease, stroke, high blood pressure, high cholesterol or high triglycerides in your family.

Frequently asked questions

What are normal lipoprotein(a) levels? For many labs, normal is below 75 nmol/L, about 30 mg/dL. From 75 to 125 nmol/L is a grey zone, and from 125 up it counts as high. Your own report may print different limits.

High lipoprotein(a): what should I do? It is a risk factor, and your overall risk can come down. Keep your LDL, blood pressure and glucose low, do not smoke and talk to your doctor. And tell your close relatives, who can test theirs too.

Can diet lower lipoprotein(a)? Hardly: your genes set it, and diet, exercise and weight loss change it very little. They do lower everything else, though, and that is what counts.

What is the difference between lipoprotein(a) and LDL cholesterol? They are similar particles, and both carry cholesterol into your arteries. Lipoprotein(a) has an extra protein attached and depends almost only on your genes. LDL, on the other hand, comes down with diet and with the most common medicines.

If mine is high, should my children and siblings get tested? It is a good idea. It is inherited, so parents, brothers, sisters and children may have it high too. A blood test is all it takes; for children, ask their paediatrician.

How often should it be checked? Usually once in a lifetime is enough: Rosa measures it once. It is repeated only in a few cases, for example with kidney disease or if the first test was before menopause.

Sources

• Kronenberg and colleagues, lipoprotein(a) in atherosclerotic cardiovascular disease and aortic stenosis: a European Atherosclerosis Society consensus statement. European Heart Journal, 2022. PMID 36036785
• Kamstrup and colleagues, genetically elevated lipoprotein(a) and increased risk of myocardial infarction. JAMA, 2009. PMID 19509380
• Langsted and colleagues, elevated lipoprotein(a) and risk of ischaemic stroke. Journal of the American College of Cardiology, 2019. PMID 31272552
• Kamstrup and colleagues, elevated lipoprotein(a) and risk of aortic valve stenosis in the general population. Journal of the American College of Cardiology, 2014. PMID 24161338