You’re probably familiar with most of the key drivers of heart disease: high blood pressure, diabetes and high LDL cholesterol. But one critical risk factor often goes unchecked: lipoprotein(a), or Lp(a).

According to Martha Gulati, MD, director of Preventive Cardiology in the Smidt Heart Institute at Cedars-Sinai, Lp(a) is a powerful and often overlooked contributor to heart disease. In fact, high levels of Lp(a) can double or even triple your risk of a heart attack.

Pronounced L-P-little-a, Lp(a) is a type of cholesterol that carries inflammatory proteins in your bloodstream. Prediman K. Shah, MD, director of the Cedars-Sinai Atherosclerosis Prevention and Management Center, calls Lp(a) a “nasty cousin” of low-density lipoprotein—also known as LDL, or bad cholesterol.  

Like LDL, Lp(a) carries a sticky protein called ApoB-100. But Lp(a) also carries an extra protein called Apo(a), which makes it even more likely to glom on to blood vessel walls, build up plaque and trigger clot formation. 

"That’s why elevated Lp(a) is linked to an increased risk of heart attack, stroke, aortic stenosis and peripheral artery disease," said Shah.

Unless you have had your Lp(a) levels tested, you won’t know your Lp(a) status. Elevated Lp(a) does not produce visible symptoms, and you can have high Lp(a) even if you follow a healthy lifestyle—and have a normal cholesterol panel.

Risk factors for elevated Lp(a) include:

• A known family history of elevated Lp(a)
• A family or personal history of early heart disease (under 45 for men and under 55 for women)
• People with very high LDL cholesterol (190 mg/dL or higher)
• A diagnosis of familial hypercholesterolemia (FH)—an inherited condition that reduces the body’s ability to remove LDL cholesterol from the bloodstream

Everyone should have their Lp(a) levels checked at least once in their lifetime. Unfortunately, according to a recent study across six academic health systems in California, fewer than 0.3% of adults ever had Lp(a) testing. Even among those with a family or personal history of heart disease, testing rates were less than 5%.

On the plus side, since 90% of Lp(a) is genetically determined, measuring Lp(a) can be a one-and-done test, depending on your gender and health status.

"Lp(a) levels remain relatively static after age 5," said Gulati. However, she added, “Women should be retested after menopause when Lp(a) levels may increase, particularly if levels prior to menopause were borderline.”

Certain chronic diseases, and the medications doctors use to treat them, can also lead to elevated Lp(a) levels.

Read: Why Is My Cholesterol High, and What Can I Do About It?

Lp(a) isn’t included in your standard cholesterol panel—your provider needs to order a specific test. The good news? Most insurance plans cover the test.

There are two ways to measure Lp(a):

• Milligrams per deciliter (mg/dL)—ideal levels are below 30 mg/dL
• Nanomoles per liter (nmol/L)—more commonly used today, with normal levels at or below 100 nmol/L

First, know you’re not alone. About 1 in 5 adults has elevated Lp(a). It’s more common among people who are Black or of South Asian descent.

Even though you can’t lower Lp(a) with diet or exercise—and there’s not yet evidence that lowering Lp(a) by itself improves your cardiovascular health—there’s still a lot you can do to reduce your overall risk of heart disease:

• Quit smoking or using tobacco
• Eat a heart-healthy, whole foods-based diet
• Exercise regularly
• Maintain a healthy weight
• Limit alcohol
• Get sufficient sleep
• Treat other risk factors such as high blood pressure, cholesterol or diabetes

The only FDA-approved treatment for Lp(a) is apheresis, an expensive and time-intensive treatment that filters Lp(a) from the blood.

"Since patients have to get the three-hour treatment every week or two, it’s only indicated in rare cases," said Shah.

Promising therapies targeting Lp(a) are currently in clinical trials, including Pelacarsen and Olsparin, which target the genetic machinery behind Lp(a) production. In the meantime, patients with elevated Lp(a) may benefit from more aggressive LDL-lowering strategies, including statins, PCSK9 inhibitors and lifestyle modifications.

Measuring Lp(a) is simple. It’s covered by insurance. And most important, it may help inspire healthful lifestyle changes.

"While we don’t yet know if lowering Lp(a) translates to fewer cardiovascular events, we do know that identifying high-risk patients allows us to intervene earlier—tightening LDL control, adjusting treatment plans and empowering patients to make informed decisions about their health," Gulati said.

Read: Health Central: Do You Know Your Triglyceride Level?