What is a lipoprotein (a) blood test?

A lipoprotein (a) test measures the level of lipoprotein (a) in your blood. A high level of lipoprotein (a) may mean you have a high risk for heart disease and stroke.

Lipoproteins are particles made of protein and fats (lipids). They carry cholesterol through your bloodstream to your cells. The two main groups of lipoproteins are called HDL (high-density lipoprotein) or "good" cholesterol and LDL (low-density lipoprotein) or "bad" cholesterol.

Lipoprotein (a) is a type of LDL. These lipoproteins carry cholesterol to your cells through your arteries (blood vessels that carry oxygen-rich blood from your heart and lungs to your body). If you have high levels of LDL particles, cholesterol can build up in your arteries and form blockages called plaques. This condition is known as atherosclerosis, or "hardening of the arteries," which means that the arteries thicken and become less flexible. It can lead to many serious medical conditions including:

• Coronary artery disease, narrow or blocked arteries in your heart
• Heart attack
• Stroke
• Peripheral arterial disease, blocked arteries in your legs or arms
• Other blood vessel diseases

Lipoprotein (a) particles are stickier than other types of LDL particles, so they may be more likely to cause blockages and blood clots in your arteries. As a result, high levels of lipoprotein (a) may mean you have a high risk for heart disease, stroke, and other serious conditions related to blockages and blood clots in your arteries.

A lipoprotein (a) blood test can give you a more accurate understanding of your risk than a routine cholesterol test that only measures your total LDL cholesterol level. That's because a routine cholesterol test may show that your LDL cholesterol level is "healthy," but if a large percentage of your LDL cholesterol is carried by lipoprotein (a) particles, your risk for heart disease and stroke could still be high.

Other names: cholesterol Lp(a), Lp(a)

What is it used for?

A lipoprotein (a) test is used to get a better understanding of your risk for heart disease, stroke, and other blood vessel diseases. But is not a routine screening test. It is usually ordered if your health care provider thinks you might be at high risk for cardiovascular problems or if having high levels of lipoprotein (a) runs in your family. Researchers are still studying how lipoprotein (a) levels affect health and when the test should be used.

Why do I need a lipoprotein (a) test?

Your provider may order the test if you have certain signs or health conditions that mean you have a high risk for blockages in your arteries, such as:

• A family health history of early heart or blood vessel disease (before age 55 for a father or brother and before age 65 for a mother or sister)
• High LDL cholesterol, even though you take medicine to lower it
• Heart or blood vessel disease, especially if your cholesterol and triglyceride (another type of fat in your body) levels are normal without taking medicine to lower them
• Signs of familial hypercholesterolemia, an inherited (passed down through families) condition that causes high cholesterol levels
• Had more than one heart attack or more than one angioplasty, a procedure to open up narrow or blocked arteries in your heart

The test may also be used to help make decisions about the risks and benefits of taking cholesterol medicine to lower your chance of developing heart and blood vessel disease.

What happens during a lipoprotein (a) test?

A health care professional will take a blood sample from a vein in your arm using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

Preparations for a lipoprotein (a) test depend on the lab doing the test. Usually, you need to fast (not eat or drink) for 9 to 12 hours before your blood is drawn. Your provider will let you know if there are any special instructions to follow.

Certain substances can affect your test results. Before you get a lipoprotein (a) test, tell your provider if you have been drinking alcohol or taking niacin supplements, aspirin, or oral estrogen hormones.

Are there any risks to the test?

There is very little risk to having a blood test. You may experience slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

A high lipoprotein (a) level may mean you have a high risk for heart and blood vessel disease, even if your cholesterol levels are normal and you are healthy.

Lipoprotein (a) levels usually don't change much over time. But test results may be affected by certain health conditions. Talk with your provider about what your test results mean.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a lipoprotein (a) test?

Your genes control how much lipoprotein (a) you make. Genes are parts of DNA in your cells that you inherit from your parents. Genes carry information that controls what you look like and how your body works. By age 5, you usually have your "adult level" of lipoprotein (a), and it tends to remain about the same for the rest of your life. For that reason, diet and exercise may not change your lipoprotein (a) levels.

But if you have a high level of lipoprotein (a), it's very important to take steps to improve your heart health. This will help lower your overall risk for heart and blood vessel problems, even though it may not change your lipoprotein (a) levels.

Your provider may suggest:

• Taking medicine to lower your LDL cholesterol if it is high
• Eating a healthy diet
• Losing weight
• Quitting smoking
• Getting regular exercise
• Reducing stress
• Lowering your blood pressure