There is a cardiovascular risk factor that affects roughly 1 in 5 people, is almost entirely genetic, is not changed by diet or exercise, is not tested in standard cholesterol panels, and is one of the strongest independent predictors of heart attack and stroke.
It is called lipoprotein(a) — written as Lp(a) and pronounced "L-P-little-a."
Most people have never heard of it. Most doctors do not test for it. And yet the European Society of Cardiology now recommends that every adult get tested at least once in their lifetime.
What Lp(a) is
Lp(a) is a special type of LDL particle. Take a regular LDL particle — the kind measured on your standard cholesterol panel — and attach an extra protein called apolipoprotein(a) to its surface. That is Lp(a).
This extra protein changes the particle's behavior in three critical ways:
- It is stickier. Apolipoprotein(a) binds to the arterial wall more aggressively than regular LDL, accelerating plaque formation.
- It is pro-inflammatory. Lp(a) carries oxidized phospholipids that trigger inflammatory signaling in the vessel wall.
- It promotes clotting. Apolipoprotein(a) is structurally similar to plasminogen — a protein involved in dissolving blood clots. Lp(a) competes with plasminogen, effectively interfering with your body's ability to break down clots. This means Lp(a) simultaneously builds plaque AND makes dangerous clots more likely.
This triple threat — atherosclerosis, inflammation, and thrombosis — is why Lp(a) is considered one of the most dangerous cardiovascular risk factors when elevated.
Lp(a) reference ranges
| Lp(a) level | Risk classification |
|---|---|
| Below 30 mg/dL (75 nmol/L) | Normal — low risk |
| 30–50 mg/dL (75–125 nmol/L) | Borderline — moderate risk |
| 50–100 mg/dL (125–250 nmol/L) | Elevated — significantly increased risk |
| Above 100 mg/dL (250 nmol/L) | Very high — major independent risk factor |
Approximately 20% of the global population has Lp(a) above 50 mg/dL. Prevalence varies by ethnicity — it is higher in people of African descent and South Asian descent.
Important note on units: Lp(a) can be reported in mg/dL or nmol/L, and the conversion is not straightforward because the molecular weight of apolipoprotein(a) varies between individuals. As a rough guide, multiply mg/dL by ~2.5 to estimate nmol/L. Always check which unit your lab uses.
Why your doctor probably hasn't tested it
Lp(a) is not included in a standard lipid panel. The typical panel measures total cholesterol, LDL-C, HDL-C, and triglycerides — but not Lp(a).
The reasons are largely historical and systemic:
- Until recently, there was no treatment. Physicians are trained to test for things they can treat. Since no medication specifically lowered Lp(a) effectively, many physicians did not see the point of testing.
- Guidelines were slow to update. The ESC now recommends testing, but US guidelines (ACC/AHA) have been slower to follow with a universal screening recommendation.
- Awareness is low. Most general practitioners did not learn about Lp(a) in medical school, and continuing education has been slow to emphasize it.
This is changing rapidly. With RNA-based therapies in late-stage clinical trials that can reduce Lp(a) by 80–100%, the rationale for testing is now overwhelming — because treatment is coming.
What the research says
The evidence for Lp(a) as a causal cardiovascular risk factor is exceptionally strong:
- Mendelian randomization studies (which use genetic variants as natural experiments) have conclusively demonstrated that genetically elevated Lp(a) causes coronary heart disease, aortic valve stenosis, heart failure, and peripheral arterial disease.
- The Copenhagen General Population Study followed over 100,000 individuals and showed a continuous, dose-dependent relationship between Lp(a) levels and cardiovascular events.
- Lp(a) and aortic stenosis: elevated Lp(a) is one of the only known modifiable (via future drugs) risk factors for calcific aortic valve disease — a condition affecting millions that currently has no drug treatment.
- Lp(a) explains residual risk: many patients who have heart attacks despite "normal" LDL-C have undetected elevated Lp(a).
The genetics: why you can't change it with lifestyle
Lp(a) levels are 80–90% determined by the LPA gene. Unlike LDL cholesterol — which responds to diet, exercise, and lifestyle — your Lp(a) level is essentially the same whether you eat perfectly, exercise daily, and have ideal body weight, or do none of those things.
This genetic determination means:
- Your Lp(a) level is roughly the same at age 20 as at age 70
- One test tells you your lifelong risk
- Siblings have similar Lp(a) levels — if yours is high, your family members should be tested
- Standard cardiovascular prevention (statin + lifestyle) does not address Lp(a) risk
Current and emerging treatments
Available now
- PCSK9 inhibitors (evolocumab, alirocumab): lower Lp(a) by approximately 20–30% as a secondary effect. They are approved for LDL-lowering, not specifically for Lp(a).
- Lipoprotein apheresis: a dialysis-like procedure that physically removes Lp(a) from the blood. FDA-approved but reserved for severe cases (familial hypercholesterolemia with coronary disease).
- Aggressive LDL-lowering: while it does not lower Lp(a), reducing overall atherogenic particle burden (via statins + ezetimibe + PCSK9i) can partially offset the cumulative risk.
Coming soon: RNA-based therapies
This is where the real revolution is. Four drugs are in advanced clinical trials that directly silence the LPA gene in liver cells, reducing Lp(a) production by 80–100%:
| Drug | Company | Mechanism | Lp(a) reduction | Status (2026) |
|---|---|---|---|---|
| Pelacarsen | Novartis/Ionis | ASO | ~80% | Phase 3 (HORIZON trial) |
| Olpasiran | Amgen | siRNA | ~95–100% | Phase 3 |
| Lepodisiran | Lilly | siRNA | ~95–100% | Phase 3 |
| Zerlasiran | Silence Therapeutics | siRNA | ~90% | Phase 2 |
These are injections given every 1–6 months. The HORIZON trial results for pelacarsen (the most advanced) are expected soon and could lead to the first FDA-approved Lp(a)-lowering therapy.
What to do if your Lp(a) is high
Step 1: Get tested
Order Lp(a) as part of your next blood panel. You only need to test once — the result is essentially permanent. In the US, it costs $30–50 through Quest or LabCorp.
Step 2: Aggressively manage all other risk factors
Since Lp(a) cannot currently be lowered meaningfully, the strategy is to minimize every other cardiovascular risk factor to reduce total cumulative risk:
- Get ApoB as low as possible — this is where statins, ezetimibe, and PCSK9i make a difference
- Optimize blood pressure — target below 120/80
- Eliminate smoking — zero tolerance
- Control metabolic health — keep HbA1c, fasting insulin, and HOMA-IR in optimal ranges
- Reduce inflammation — keep hs-CRP below 1.0 mg/L through exercise, diet, and stress management
- Exercise regularly — 150+ minutes of zone 2 cardio per week
Step 3: Consider advanced imaging
If your Lp(a) is high, a coronary artery calcium (CAC) score can tell you whether plaque has already accumulated. This helps quantify actual risk beyond the blood number.
Step 4: Watch for approved therapies
With RNA drugs in Phase 3, the first specific Lp(a)-lowering medication could be available within the next 1–3 years. If your Lp(a) is very high (above 100 mg/dL), discuss with a lipidologist whether early access or clinical trial enrollment makes sense.
How Merios helps
Upload your lipid panel to Merios and we extract Lp(a) alongside ApoB, LDL-C, HDL-C, triglycerides, and hs-CRP. Track your overall cardiovascular risk profile over time, even if Lp(a) itself stays constant — the goal is to see that every modifiable risk factor is trending in the right direction.
Track your Lp(a) with Merios →
This article is for informational purposes only and does not constitute medical advice. Discuss Lp(a) testing and management with a qualified physician or lipidologist.