Lipoprotein (a)

Lipoprotein (a) testing measures the amount of a specific particle, known as lipoprotein (a), in the blood. An elevated level of lipoprotein (a) is linked to a higher risk of health problems like heart disease, heart attack, and stroke.

Lipoprotein (a) testing is most often used to estimate the likelihood of cardiovascular disease. However, it is not a routine type of cholesterol test and is generally performed in people who are already believed to be at greater risk of cardiovascular problems.

Purpose of the test

The purpose of a lipoprotein (a) test is to evaluate whether a person has high levels of lipoprotein (a) that can contribute to cardiovascular diseases like heart attack and stroke.

Lipoprotein (a) tests are mainly used for screening, which describes testing to identify health problems before they cause signs or symptoms. The goal of screening patients for lipoprotein (a) is early detection of potential cardiovascular problems. Screening is most commonly recommended for people who are already believed to have an elevated risk of cardiovascular disease.

A test for lipoprotein (a) can also inform treatment decisions related to lowering cholesterol and reducing the risk of heart problems. For example, a doctor and patient may consider lipoprotein (a) levels when deciding whether to use cholesterol-lowering medications. In addition, lipoprotein (a) testing may be recommended if LDL cholesterol levels do not decrease as much as expected when taking cholesterol-lowering medications.

What does the test measure?

A lipoprotein (a) test measures the amount of lipoprotein (a) particles in a sample of blood.

Lipoprotein (a) is one of several kinds of lipoproteins. Lipoproteins are a mixture of fat and protein that transport cholesterol in the blood to cells throughout the body. Cholesterol is a waxy substance that enables normal cell function, but too much of certain kinds of lipoproteins and cholesterol can build up and damage arteries.

Lipoprotein (a) is classified as a type of low-density lipoprotein (LDL). Cholesterol carried in LDL particles is known as “bad” cholesterol because of its association with cardiovascular disease. While lipoprotein (a) particles can transport cholesterol, the lipoprotein (a) particles themselves can also contribute to the buildup of plaque in the arteries, heightening the risk of heart attacks and stroke.

Lipoprotein (a) levels are driven by individual genetics. Unlike cholesterol levels, which are frequently linked to diet and other lifestyle choices, a person’s lipoprotein (a) levels are mostly determined by genes that can be passed down through families.

When should I get a lipoprotein (a) test?

Lipoprotein (a) testing is not a routine type of cholesterol test, and it is usually reserved for people who have already been determined to be at higher risk of cardiovascular problems.

There is no expert consensus about when you should get a lipoprotein (a) test. Different medical organizations have distinct recommendations, but testing is more likely to be recommended if you have risk factors for cardiovascular disease such as:

• Past diagnosis of cardiovascular disease
• Very high levels of LDL cholesterol
• Family history of cardiovascular disease, especially if it occurred early in life and in more than one first-degree relative
• High potential of having familial hypercholesterolemia, a hereditary disorder causing high levels of “bad” LDL cholesterol

A lipoprotein (a) test may provide information that can help assess your cardiovascular disease risk. You may also be advised to have lipoprotein (a) testing if you and your doctor are discussing the benefits and risks of medications to lower your cholesterol. For example, if you take cholesterol medications but have not seen the expected decrease in “bad” LDL cholesterol, the doctor may suggest lipoprotein (a) testing to better evaluate your cardiovascular health risks.

How to get tested

Lipoprotein (a) testing is performed in a medical setting like a hospital, doctor’s office, or laboratory. The test is conducted after being ordered by a doctor.

Can I take the test at home?

Some at-home test kits are available for lipoprotein (a) testing. These self-collection tests involve obtaining a blood sample by pricking your finger with a tiny needle. After placing a drop of blood on a special test paper, you put the paper into an included mailer that is sent to a laboratory for analysis.

A test report showing your lipoprotein (a) level is accessed online and usually available within a week after your blood sample is received by the company’s lab.

How much does the test cost?

The cost of lipoprotein (a) testing depends on factors including where the test is done, whether any other measurements are included, and whether testing is covered by health insurance. The complete cost of lipoprotein (a) testing can include charges for the blood draw, office visits, and laboratory analysis of the test sample.

Because lipoprotein (a) is not part of routine cholesterol testing, some insurance plans may not pay for testing even if it is prescribed by your doctor. For that reason, you should talk to your insurance company before testing.

A lipoprotein (a) test is performed with a blood sample. The sample is normally taken by a health professional with a routine needle blood draw at a doctor’s office, laboratory, or hospital.

Before the test

Pretest instructions for a lipoprotein (a) test can vary based on the laboratory’s requirements and whether the test includes other measurements in addition to lipoprotein (a).

Sometimes you will be asked to fast before a lipoprotein (a) test, which means consuming no food or drinks besides water for 9 to 12 hours beforehand. In other cases, fasting may not be required.

Some types of drugs may affect the test, so you should review with your doctor any prescription or over-the-counter medications and dietary supplements that you are taking.

Because test preparations can vary, it is essential to follow any specific pretest instructions provided by your doctor or the laboratory conducting your test.

During the test

A lipoprotein (a) test involves a routine blood draw during which a small sample of blood is taken from a vein in your arm.

To begin the test, a nurse or technician usually ties a band around the upper part of your arm, which increases blood flow in your veins. They use an antiseptic wipe to disinfect the skin near a vein and then insert a needle into the vein. A vial of blood is collected, and the needle is removed.

The entire blood draw usually takes less than a few minutes. There may be some pain or a sting when the needle is inserted and withdrawn, but it is rare to have any serious or long-lasting side effects.

After the test

Once your blood has been drawn and the needle has been removed, a bandage or cotton swab will be used to apply pressure and stop any continued bleeding.

If you are instructed to fast before the test, it can be helpful to bring a snack to eat right after the blood draw. You can go back to driving and most normal activities without restrictions once the test is over.

Some pain, swelling, or bruising may occur in your arm, but these effects are usually mild and do not last long. If you have any signs of an infection or other worsening effects from a blood draw, contact your doctor directly.

Receiving test results

The results from a lipoprotein (a) test are usually ready within a few business days after the laboratory receives your blood sample.

Your doctor may review the results with you at an appointment or by phone. You may also receive a detailed lipoprotein (a) test report by mail or via an online health portal.

Interpreting test results

Depending on the laboratory method used, lipoprotein (a) levels are reported in milligrams per deciliter (mg/dL) of blood or in nanomoles per liter (nmol/L) of blood.

The laboratory method can also affect the reference range for lipoprotein (a), so you should look closely at the test report to see the range of lipoprotein (a) levels considered normal for the specific laboratory that conducted your test. Your doctor can review the results with you and explain whether they were normal or abnormal.

High levels of lipoprotein (a) are considered to be a potential contributor to cardiovascular problems like the buildup of plaque in the arteries, heart attack, and stroke. In general, lipoprotein (a) levels that are above 50 mg/dL or 125 nmol/L are considered to be a risk factor for cardiovascular disease.

Lipoprotein (a) levels are determined primarily by genetics and generally cannot be changed by diet or medication. However, people with very high levels of lipoprotein (a) may be advised to take more aggressive measures to lower their levels of “bad” LDL cholesterol.

Interpreting a lipoprotein (a) test result requires considering many factors including your age, results from other cholesterol tests, additional risk factors for cardiovascular disease, and your overall health. Your doctor is in the best position to review these considerations and explain the significance of your lipoprotein (a) test result.

Are test results accurate?

No medical test is 100% accurate, but lipoprotein (a) testing can be an important part of cardiovascular risk assessment.

Lipoprotein (a) levels are generally stable over time, but patients with chronic kidney disease may have increased levels. Test results may also be affected by a current illness and some other individual health circumstances.

Your doctor can address any specific questions that you have about the test and the accuracy of your test results.

Do I need follow-up tests?

Follow-up after lipoprotein (a) testing can depend on your test results and other tests that may have been done in the past. Abnormal test results may warrant further evaluation of your heart and cardiovascular health.

While other types of cholesterol tests are sometimes repeated over time, it is less common for lipoprotein (a) tests to be repeated because lipoprotein (a) levels usually do not change significantly over time.

Questions for your doctor about test results

After a lipoprotein (a) test, you can discuss the results with your doctor. The following questions may help you understand the test result:

• What was my lipoprotein (a) level?
• Does my lipoprotein (a) test result change how you evaluate my cardiovascular disease risk?
• Do you recommend any additional testing?
• Are there any medications or lifestyle changes that you recommend based on my lipoprotein (a) and other cholesterol levels?

Comparing and contrasting a lipoprotein (a) test and a lipid panel

A lipid panel is a common test that is used to assess cholesterol levels. The standard lipid panel includes four components:

• Total cholesterol
• High-density lipoprotein (HDL) cholesterol
• Low-density lipoprotein (LDL) cholesterol
• Triglycerides.

Lipoprotein (a) is a type of LDL particle, but lipoprotein (a) is not measured in a typical lipid panel. A lipid panel is a more routine test to evaluate cardiovascular disease risk. It is often used in people with no symptoms or risk factors.

In contrast, the role of lipoprotein (a) testing is less clearly established, and lipoprotein (a) tests are generally only done in people who are known to have an elevated risk of cardiovascular problems.

Comparing and contrasting a lipoprotein (a) test and a low-density lipoprotein (LDL) cholesterol test

A test of low-density lipoprotein (LDL) cholesterol determines the amount of cholesterol found in LDL particles. A lipoprotein (a) test doesn’t measure cholesterol but rather the amount of lipoprotein (a) particles.

Lipoprotein (a) is one type of low-density lipoprotein. LDL particles, including lipoprotein (a), carry cholesterol in the blood. Cholesterol in LDL particles is considered to be a type of “bad” cholesterol that can collect in the arteries and contribute to serious cardiovascular disease.

Because lipoprotein (a) is a type of LDL particle, an LDL cholesterol test that evaluates the amount of cholesterol in all types of LDL particles will count the cholesterol inside lipoprotein (a) particles. However, an LDL cholesterol test does not evaluate the level of lipoprotein (a) particles themselves.

LDL cholesterol levels are often the focus of cardiovascular risk assessment and cholesterol-lowering treatment. For most people, LDL cholesterol can be lowered by changing lifestyle habits and/or with medications.

Lipoprotein (a) levels are determined predominantly by genetics and, unlike LDL cholesterol, are not significantly affected by lifestyle or medication. Elevated lipoprotein (a) is considered to be a risk factor for cardiovascular disease independent of other cholesterol levels.

For some patients, lipoprotein (a) testing may be a consideration when determining the optimal approach to reducing LDL cholesterol.

Comparing and contrasting a lipoprotein (a) test and a non-high-density lipoprotein (non-HDL) cholesterol test

A lipoprotein (a) test measures only the number of lipoprotein (a) particles in the blood. While some of those lipoprotein (a) particles carry cholesterol, a lipoprotein (a) test does not measure cholesterol levels.

A non-high-density lipoprotein (non-HDL) cholesterol test assesses the total amount of cholesterol in the blood that is not carried in HDL particles. Non-HDL cholesterol is considered “bad” cholesterol.

Non-HDL cholesterol includes cholesterol found in lipoprotein (a) particles. It also includes cholesterol carried in low-density lipoproteins, intermediate-density lipoproteins (IDL), and very low-density lipoproteins (VLDL).