Lp(a): The Cardiovascular Risk Factor Your Doctor Probably Never Tested

I’ve counseled hundreds of patients who believed they were doing everything right. Normal LDL. Blood pressure controlled. Non-smoker. Exercise three times a week. And then, at 52, a heart attack.

What those patients often had in common — and what no one had ever checked — was elevated lipoprotein(a), or Lp(a) (pronounced “L-P-little-a”). It’s not a niche academic curiosity. It affects roughly 1 in 5 people globally, it’s largely determined by genetics, and it substantially increases the risk of heart attack, stroke, and aortic valve disease. Yet study after study confirms the same uncomfortable truth: the vast majority of people with elevated Lp(a) have never been tested.

This is one of the most consequential gaps in routine preventive care, and I want to walk you through exactly what Lp(a) is, why it matters, and what you can actually do about it.

What Is Lp(a)?

Lp(a) is a lipoprotein particle — structurally, it looks a lot like LDL. It has a core of cholesterol and triglycerides surrounded by a phospholipid shell. What makes it unique is an additional protein called apolipoprotein(a), or apo(a), which is bound to the ApoB-100 protein on the surface of the LDL-like particle via a disulfide bond.

That apo(a) attachment is what makes Lp(a) particularly dangerous. It gives the particle both atherogenic (plaque-building) and thrombogenic (clot-promoting) properties. Structurally, apo(a) has a strong resemblance to plasminogen — the protein your body uses to break down clots. Because of this molecular mimicry, Lp(a) may compete with plasminogen at clot sites, interfering with your body’s ability to dissolve blood clots.

How Lp(a) Drives Cardiovascular Disease

Elevated Lp(a) damages cardiovascular health through several mechanisms:

Atherosclerosis acceleration. Lp(a) particles deposit in arterial walls and contribute to plaque formation. They also oxidize easily, and oxidized Lp(a) activates inflammatory pathways that accelerate atherosclerosis.

Thrombosis promotion. The apo(a) component inhibits fibrinolysis — the process of breaking down clots. This shifts the hemostatic balance toward clot formation, which is why elevated Lp(a) is associated with thrombotic events even in people with otherwise clean arteries.

Aortic valve disease. This is less discussed but clinically important. Elevated Lp(a) is one of the strongest known risk factors for calcific aortic valve stenosis — a progressive narrowing of the aortic valve that can ultimately require replacement. The Mendelian randomization data here are compelling: it appears to be a causal relationship, not just association.

Clinical Callout: Mendelian randomization studies use genetic variants as natural “experiments” to test causality. The data on Lp(a) and cardiovascular disease are among the most robust in this literature — genetically elevated Lp(a) causes higher rates of ASCVD and aortic stenosis, independent of other risk factors. This isn’t statistical noise.

How Common Is Elevated Lp(a)?

Globally, approximately 20% of the population — around 1.4 billion people — has an Lp(a) level above 50 mg/dL, the threshold most guidelines consider “elevated.” That’s not a rare genetic disorder. That’s one in five of your colleagues, family members, and patients.

The distribution is not uniform across populations. People of African descent have significantly higher average Lp(a) levels than people of European descent, which likely contributes — in part — to disparities in cardiovascular outcomes. South Asian populations also tend to have elevated levels relative to European populations.

Despite this prevalence, the American Heart Association estimates that fewer than 1% of US patients have ever had an Lp(a) level tested. In my clinical experience, that number feels generous. Most primary care physicians simply don’t order it. It’s not on the standard lipid panel. It’s not in most EHR order sets. Many clinicians were trained in an era when there were no effective treatments, which led to the reasonable but now outdated assumption that testing without actionability wasn’t worth it.

That calculus has changed.

Who Should Get Tested?

My position: everyone should be tested at least once. Major cardiology societies are moving in this direction. The European Atherosclerosis Society (EAS) consensus statement recommends measuring Lp(a) at least once in every adult. The 2018 AHA/ACC cholesterol guidelines list Lp(a) as a “risk-enhancing factor” that should be considered in borderline-risk patients to help guide statin decisions.

That said, there are specific populations where testing is urgent:

• Family history of premature cardiovascular disease (defined as a first-degree male relative with CVD before age 55, or female relative before age 65)
• Personal history of ASCVD — heart attack, stroke, or peripheral artery disease — especially if the event occurred at a young age or without obvious risk factors
• Familial hypercholesterolemia — there’s significant genetic overlap, and elevated Lp(a) compounds the risk substantially
• Calcific aortic valve disease — Lp(a) is now a recognized causal risk factor; baseline testing is warranted
• Unexplained high cardiovascular risk — someone whose risk calculators come back elevated but whose traditional risk factors don’t fully explain it

Clinical Callout: If you’ve had a cardiovascular event and your LDL was “not that high,” Lp(a) deserves serious scrutiny. Residual cardiovascular risk after statin therapy is one of the most clinically important unsolved problems in cardiology, and elevated Lp(a) accounts for a significant portion of that unexplained risk.

How to Get Tested — and How to Interpret Results

The Test Itself

An Lp(a) test is a simple blood draw. It’s available through standard labs and increasingly through direct-to-consumer (DTC) platforms. You don’t need a cardiologist’s referral, though interpretation benefits from one.

The units matter — a lot. Lp(a) is reported in two ways:

• mg/dL — measures the mass of the entire Lp(a) particle
• nmol/L — measures the number of Lp(a) particles (molar concentration)

Because apo(a) comes in variable-sized isoforms, two people can have the same mg/dL reading but different particle counts — and particle count better reflects cardiovascular risk. The European guidelines and most lipidologists now prefer nmol/L, with a threshold of >125 nmol/L considered elevated (roughly equivalent to >50 mg/dL, though conversion is imprecise).

When you get your result, ask for it in nmol/L if possible. If you only have mg/dL, the general clinical thresholds to know:

Level	Interpretation
< 30 mg/dL	Low risk
30–50 mg/dL	Borderline; consider clinical context
> 50 mg/dL	Elevated; risk-enhancing
> 100 mg/dL	High risk; aggressive risk management warranted

Testing Once Is Usually Enough

Unlike LDL, Lp(a) doesn’t meaningfully change with diet or lifestyle. It’s set by your genetics — specifically, the LPA gene on chromosome 6. You’ll see fluctuations of 10–15% in repeat measurements due to lab variability, but the trajectory of your level across decades is largely fixed. If you test once and you’re 32 mg/dL, you don’t need to retest every year. If you’re at 90 mg/dL, the number itself isn’t going to change dramatically — what changes is the context around it and the therapies available to you.

What Can You Actually Do About It?

This is where I want to be direct with you, because there’s a lot of noise online and the honest clinical answer is: lifestyle has almost no impact on Lp(a). This is not defeatism — it’s genetics. The usual levers that move cardiovascular risk — losing weight, eating less saturated fat, exercising more — do virtually nothing to Lp(a) levels. Some studies show slight reductions with low-carbohydrate diets; a few show that estrogen therapy lowers Lp(a) in postmenopausal women. But we’re talking about modest effects in specific populations. If your Lp(a) is elevated, diet and exercise will not fix it.

What can you do?

1. Aggressively Manage Everything Else

If you have elevated Lp(a), the clinical imperative is to reduce every other modifiable cardiovascular risk factor as aggressively as possible. Bring your LDL down. Hard. If your Framingham risk suggests a statin, you start a statin. If you’re on a statin and LDL is still >70 mg/dL, you consider adding ezetimibe or a PCSK9 inhibitor. Blood pressure control becomes non-negotiable. If you smoke, stopping is mandatory. Metabolic syndrome needs to be treated. The strategy is to take every risk factor you can control and eliminate it, because Lp(a) isn’t going anywhere.

2. PCSK9 Inhibitors

PCSK9 inhibitors — evolocumab (Repatha) and alirocumab (Praluent) — primarily work by dramatically reducing LDL, but they also lower Lp(a) by approximately 20–30%. This is a secondary benefit, not the primary mechanism, but it’s meaningful for high-risk patients. If you’re already a candidate for PCSK9 inhibition based on your LDL and cardiovascular history, the Lp(a)-lowering effect is an additional argument in their favor.

Clinical Callout: Niacin used to be used to lower Lp(a) — it does reduce levels by 20–30% — but the AIM-HIGH and HPS2-THRIVE trials showed no reduction in cardiovascular events with niacin added to statin therapy, along with significant adverse effects. Niacin is not recommended for Lp(a) management.

3. Emerging RNA-Based Therapies — The Most Important Development in Lipidology in a Decade

Two RNA-based therapies are in late-stage development specifically targeting Lp(a):

Pelacarsen (Novartis) is an antisense oligonucleotide (ASO) that targets LPA mRNA in the liver, reducing Lp(a) synthesis. Phase 2 data showed ~80% reduction in Lp(a) levels. The pivotal Phase 3 trial (Lp(a)HORIZON) completed enrollment and results are expected in 2025–2026.

Olpasiran (Amgen) is a small interfering RNA (siRNA) targeting LPA mRNA. Phase 2 data showed up to 97% reduction in Lp(a) with a convenient once-quarterly dosing schedule. Phase 3 (OCEAN(a)-OUTCOMES) is underway.

Lepodisiran (Eli Lilly) is another siRNA showing ~94% reduction with a potential twice-yearly dosing schedule — among the most durable effects seen in the field.

If the Phase 3 cardiovascular outcomes data confirm what the Phase 2 biomarker data suggest, we may have approved Lp(a)-specific therapies within the next 1–2 years. For patients with significantly elevated Lp(a) and established cardiovascular disease, this could be transformative.

4. Consider Aspirin — With Nuance

Given Lp(a)‘s thrombogenic properties, low-dose aspirin has some mechanistic rationale in patients with significantly elevated Lp(a), particularly those with existing ASCVD. This is a judgment call that should involve your physician — aspirin’s bleeding risk is real — but the thrombotic mechanism of Lp(a) makes antiplatelet therapy more conceptually relevant here than it is for pure atherosclerotic risk.