Apolipoprotein A1

What is apolipoprotein A1?

Apolipoprotein A1 (apoA1) is the major protein in HDL (high-density lipoprotein). Your liver and small intestine make this protein. It plays a role in getting extra cholesterol out of your tissues and to your liver for removal. This helps prevent atherosclerosis and lowers your risk of heart disease.

Another apolipoprotein A1 function is to help HDL form. Every HDL particle has two to five molecules of apolipoprotein A1. ApoA1 makes chemical bonds with lipids and determines HDL’s shape. This shape can be flat or round, depending on how many lipids apoA1 collects.

ApoA1 also reduces inflammation in cells that line your blood vessels and encourages these cells to grow. Limiting inflammation is important for keeping your blood vessels healthy. Blood moves through arteries and veins more easily when they’re not inflamed.

This protein helps widen your blood vessels, too, which helps your blood flow better through them.

How do I find out my apoA1 level?

Your healthcare provider will order an apolipoprotein A1 blood test​ to find out your level. This isn’t a routine test, but the information from it can be useful in certain cases. The results can be helpful in figuring out heart disease risk in people with a personal or family history of high cholesterol.

You may also get the test if someone in your biological family has had heart disease, like a heart attack. Heart disease tends to run in families.

Another reason for this blood test is to check your progress. The results can tell your provider if the medicine you’re taking for high cholesterol is working.

Your provider may also look at your level of apolipoprotein B. A high ratio of apoB to apoA1 has a link to a higher risk of heart and blood vessel disease. Some researchers believe this may even be better at predicting blood vessel disease than the total cholesterol to HDL cholesterol ratio.

What is the reference range?

The normal range for apolipoprotein A1 is 100 to 150 milligrams per deciliter (mg/dL). If your apolipoprotein A1 level is low, you may also have a low level of HDL in your blood. Because HDL and apoA1 remove cholesterol from your body, low levels of these can mean you have a higher risk of heart disease.

A high level of apolipoprotein A1 is a good thing. It usually doesn’t cause issues.

What causes low apolipoprotein A1?

Some people have a genetic issue in their family that keeps their apoA1 low. But in most cases, low apolipoprotein A1 comes from:

• Certain medicines, like beta-blockers and diuretics
• Kidney failure
• Unmanaged diabetes
• Use of tobacco products

What causes high apolipoprotein A1?

High apoA1 can run in your family. But most likely, it comes from:

• Certain medicines, like estrogen
• Physical activity
• Pregnancy
• Statins and other drugs for high cholesterol
• Weight loss

How can I increase my apoA1?

You can change your daily habits to improve your apolipoprotein A1 level. Researchers have found higher levels of apoA1 in people who:

• Are physically active
• Don’t use tobacco products
• Have a low body mass index (BMI)
• Follow the Mediterranean diet