Lipoprotein(a) [Lp(a)]: A lifelong risk marker often checked once

What is lipoprotein(a) [Lp(a)]?

Lp(a) forms when an additional protein called apolipoprotein(a) attaches to an LDL-like lipid–protein particle. The small “a” in the name comes from that protein. This structure makes Lp(a) a risk marker distinct from standard LDL cholesterol.

More than 90% of the variation in Lp(a) level can be explained by genetic differences around the LPA gene. That is why two people who live in the same household and eat similarly can have very different Lp(a) results. Because the level remains relatively stable in most adults, the test is not usually repeated at short intervals.^[3]

The phrase “hidden risk” refers to the fact that Lp(a) can be high without symptoms. It does not mean that elevated Lp(a) is a disease by itself, or that a cardiovascular event is inevitable.

Why can Lp(a) matter when LDL cholesterol looks normal?

A standard cholesterol panel measures total cholesterol, LDL, HDL and triglycerides; Lp(a) is usually not reported as a separate result on that panel. Therefore Lp(a) elevation can remain unrecognized even when LDL cholesterol is at target.

Epidemiologic and genetic studies show that atherosclerotic cardiovascular disease risk rises gradually as Lp(a) increases. The association is not limited to coronary artery disease and myocardial infarction; it is also linked to ischemic stroke and calcific aortic valve disease.^[3,5–8]

An important distinction: Lp(a) is not a standalone risk calculator. It is interpreted together with age, blood pressure, smoking, diabetes, LDL cholesterol, kidney function, family history and any prior cardiovascular disease.

Who should have an Lp(a) test?

The 2026 ACC/AHA dyslipidemia guideline gives a Class I recommendation for measuring Lp(a) at least once in all adults. The 2022 European Atherosclerosis Society (EAS) consensus statement likewise recommends at least one measurement in adults, preferably at the time of the first lipid assessment.^[1,3]

Although a once-in-a-lifetime approach for everyone is endorsed, testing should not be delayed in particular groups:

• People with premature heart attack, stroke or other atherosclerotic cardiovascular disease in themselves or their family
• Those with very high Lp(a) identified in the family
• People with a diagnosis or suspicion of familial hypercholesterolemia
• Those with unexpectedly early aortic valve stenosis, or a family history of that finding
• People who have had a cardiovascular event despite well-controlled LDL cholesterol
• People whose overall cardiovascular risk is borderline and for whom an additional risk marker could change the decision^[1,3,4]

When high Lp(a) is found in one person, measuring it in first-degree relatives — parents, siblings and children — can also be useful. This is called cascade or family screening.^[1,3]

How is the Lp(a) test done?

Lp(a) is measured from a blood sample. Fasting is not required for the Lp(a) assay itself, although other blood tests ordered at the same time may require fasting.^[1] The laboratory may report the result in mg/dL or nmol/L.

Whenever possible, a standardized method that is less affected by apolipoprotein(a) isoform size is preferred. When interpreting the result, the laboratory’s method and the unit it reports should be preserved.^[1,3]

What should Lp(a) be? How are results interpreted?

The relationship between Lp(a) and risk is continuous: there is no single cut-point below which risk is absent and above which disease is certain. Practical ranges are still used to support clinical decisions.

The European and U.S. nmol/L thresholds in this table are not identical. An important reason is variation in assay methods and in apolipoprotein(a) particle size from person to person.^[1–4]

Why mg/dL and nmol/L should not be converted with a fixed factor

There is no universal conversion factor between mg/dL and nmol/L for Lp(a). mg/dL reflects particle mass, whereas nmol/L reflects molar concentration based on particle number. Because apolipoprotein(a) size differs between individuals, “multiply by this number” calculations can lead to misclassification.^[1,3]

The safest approach is to interpret the result in the unit reported by the laboratory, using the thresholds that apply to that unit.

Is the test really done only once?

In most adults, a single reliable measurement is enough. Still, “once in a lifetime” is not an absolute rule. A clinician may consider a repeat measurement when:

• The first result is very close to a decision threshold
• The first test was drawn during acute infection or marked inflammation
• A secondary condition that can affect Lp(a) is present, such as kidney, liver or thyroid disease
• Pregnancy or the menopausal transition may be influencing the level
• There is technical concern about the assay method or the laboratory result^[1,3]

Whether to retest depends on the clinical context and on whether the first result would change treatment decisions.

What happens if Lp(a) is high?

The first step after a high result is not to focus only on the Lp(a) number, but to reassess overall cardiovascular risk. Prior heart attack or stroke, LDL cholesterol, blood pressure, blood glucose, smoking, kidney function and family history are considered together.^[1–4]

The main elements of current management are:

1. Managing LDL cholesterol and other risk factors to target: The additional risk linked to Lp(a) makes careful control of modifiable risks especially important.
2. Not smoking, staying active and eating a balanced diet: These steps may not lower Lp(a) substantially, but they reduce overall cardiovascular risk.
3. Monitoring blood pressure, diabetes and body weight: The effect of Lp(a) can grow when other risks are also present.
4. Not changing medications on the basis of the result alone: Treatment decisions rest on overall risk and existing conditions.

Statins do not lower Lp(a); a small increase may be seen in some people. Even so, because of the cardiovascular benefit they provide by lowering LDL cholesterol in appropriate patients, high Lp(a) is not a reason to stop a statin.^[1,3]

PCSK9 inhibitors can produce a moderate reduction in Lp(a), but their primary indication and treatment decision still rest on LDL cholesterol and the person’s cardiovascular risk. Lipoprotein apheresis is a specialized option considered in selected very-high-risk patients with progressive cardiovascular disease, within country-specific criteria.^[1,3,4]

Are there new drugs that lower Lp(a) directly?

Newer molecules such as pelacarsen, olpasiran and lepodisiran target apolipoprotein(a) production in the liver. Phase 2 trials have shown substantial reductions in Lp(a) levels.^[9–11] Lowering a laboratory value is not the same as reducing heart attack, stroke or cardiovascular death.

As of 24 August 2026, no therapy that specifically lowers Lp(a) has been proven to reduce cardiovascular events and entered routine use for that purpose. For pelacarsen, results of the Lp(a)HORIZON outcomes trial are not yet posted on ClinicalTrials.gov; outcomes trials for olpasiran (OCEAN(a)-Outcomes) and lepodisiran (ACCLAIM-Lp(a)) are ongoing.^[12–14]

Because this field is changing quickly, trial registries and regulatory status should be rechecked at publication and with each update.

What a high Lp(a) result does not mean

A high Lp(a) result does not mean:

• That arterial blockage is already present
• That heart attack or stroke is inevitable
• That medication must be started on that finding alone
• That healthy lifestyle habits no longer matter
• That everyone in the family has the same value

The result makes visible one part of the lifelong inherited risk a person carries. Its value is in helping decide how closely other risk factors should be managed going forward.