A routine cholesterol test provides important information about cardiovascular risk, but it may not tell the whole story.
One important risk factor that is not usually included in a standard cholesterol panel is lipoprotein(a), or Lp(a). Even when routine cholesterol levels are within the expected range, an elevated Lp(a) level can be associated with increased cardiovascular risk, including heart attack and stroke.
Understanding your Lp(a) level can be an important part of the picture when assessing your overall, long-term cardiovascular risk.
What is lipoprotein(a)?
Lipoproteins are tiny particles, made up of fat and protein, that move through our blood, carrying fats such as cholesterol and triglycerides, to our cells. High-density lipoproteins (HDL) are known as ‘good’ cholesterol, as they help transport excess cholesterol away from the arteries. Low-density lipoproteins (LDL) are known as ‘bad’ cholesterol, as high levels can contribute to plaque buildup in your arteries.
Lipoprotein(a) or Lp(a) is another type of lipoprotein that is like LDL, but it carries an additional protein called apolipoprotein(a).
Your Lp(a) level is predominantly inherited. This means that even if your level of LDL is low, and you are fit, healthy, and exercise regularly, you may still have a high Lp(a) level.
Therefore, elevated Lp(a) is considered an inherited, largely genetic risk factor for cardiovascular disease.
Your Lp(a) level usually remains stable throughout your lifetime, meaning a single measurement can be enough to provide useful insights into your long-term risk.
Can you have high Lp(a) if your cholesterol is normal?
Yes, which is one of the reasons why knowing your Lp(a) is an important part of assessing your cardiovascular risk. Standard cholesterol panels typically measure LDL, HDL, total cholesterol and triglycerides, but Lp(a) isn’t routinely included.
Your cholesterol panel may come back as normal. But you may still be at an increased risk of cardiovascular disease if your Lp(a) is high.
It’s important to note that a high Lp(a) doesn’t mean you will go on to develop heart disease, but it is an important factor that your doctor will take into consideration when assessing your overall risk.
Why does high Lp(a) matter?
Elevated Lp(a) can promote atherosclerosis, in which plaque builds up in the arteries. It is also linked to inflammatory and calcific processes and may contribute to thrombosis (blood clot formation).
Over time, this can increase the risk of several cardiovascular problems, such as heart attack, stroke, coronary artery disease, peripheral artery disease, and aortic stenosis.
What is an Lp(a) test?
An Lp(a) test is a simple blood test that measures the amount of Lp(a) in your blood. The result will be reported in nanomoles per liter (nmol/L) or milligrams per deciliter (mg/dL). Because Lp(a) is inherited and usually remains stable, you don’t need to repeat the test regularly.
What is considered a high Lp(a) level?
Current American College of Cardiology and American Heart Association (ACC/AHA) guidelines consider an Lp(a) level of 125 nmol/L (50 mg/dL) or higher to be a risk-enhancing factor associated with increased cardiovascular risk. Importantly, cardiovascular risk increases as Lp(a) rises, rather than beginning at a single threshold.
Higher Lp(a) levels are associated with progressively greater cardiovascular risk. ACC/AHA guidelines state that an Lp(a) level of 250 nmol/L (100 mg/dL) is associated with at least a two-fold higher long-term risk of heart attack or stroke. Because nmol/L measures particle concentration and mg/dL measures mass, the two units should not be converted using a single fixed conversion factor.
What is a dangerously high lipoprotein(a)?
There is no level of Lp(a) that means you will develop cardiovascular disease – the risk generally increases as levels rise.
When assessing your risk, your doctor will take other factors, such as LDL cholesterol, blood pressure, blood sugar, family history and existing heart disease, into consideration.
Is Lp(a) affected by lifestyle?
Unlike LDL cholesterol, Lp(a) levels are largely determined by your genes. Diet, exercise and other lifestyle choices usually have little effect on your Lp(a) level.
However, this doesn’t mean that a healthy lifestyle isn’t important. If you do have a high Lp(a) level, managing the risk factors that you can change is very important for those living with an increased risk of cardiovascular disease.
Your doctor may recommend:
- Exercising regularly
- Maintaining a healthy weight
- Eating a heart-healthy diet
- Quitting smoking
- Keeping your LDL cholesterol level at an appropriate level
- Managing your blood pressure
- Controlling diabetes or blood sugar levels
While these lifestyle changes won’t lower your Lp(a), they can help to reduce your overall risk of cardiovascular disease.
Who should have an Lp(a) test?
Current guidance supports measuring Lp(a) at least once in adulthood to help assess cardiovascular risk. Testing is particularly important in people with a family history of premature cardiovascular disease or high Lp(a), familial hypercholesterolemia (an inherited condition that causes very high levels of LDL cholesterol), premature cardiovascular disease, or when additional information may help refine cardiovascular risk. If Lp(a) is elevated, testing first-degree family members may also be recommended.
What happens if your Lp(a) is high?
If your Lp(a) is high, it does not mean that you will definitely develop cardiovascular disease. Lp(a) is one part of your overall risk profile, but an elevated result is important because it can identify a need for more intensive prevention.
Because Lp(a) is largely inherited and lifestyle changes usually have little effect on its level, management focuses on reducing overall cardiovascular risk, particularly through intensive control of LDL cholesterol, blood pressure, diabetes, smoking and other modifiable risk factors.
Several therapies designed specifically to lower Lp(a) are currently being studied, but their role will depend on evidence that lowering Lp(a) translates into fewer cardiovascular events.
Know your numbers – including Lp(a)!
A cholesterol test is important, but it may not tell the whole story. Having your Lp(a) measured at least once during adulthood can give you and your doctor a more complete picture of your lifetime cardiovascular risk.
Knowing your Lp(a) level gives you and your doctor the opportunity to better understand your risk and act on the things you can control.
Understanding your Lp(a), alongside LDL cholesterol, HDL cholesterol, triglycerides and other cardiovascular risk factors can help to build a more complete picture of your heart health.