Apolipoprotein A

Apo A-1, apolipoprotein a-1 

This test measures the amount of apolipoprotein A in your blood. It helps your healthcare provider figure out your risk for cardiovascular disease.

Apolipoprotein A is a protein carried in HDL ("good") cholesterol. It helps start the process for HDL to remove bad types of cholesterol from your body. In this way, apolipoprotein A can help to lower your risk for cardiovascular disease. Apolipoprotein A levels can be measured. But it's more common to measure the HDL and LDL ("bad") cholesterol when looking at cardiovascular risk.     

You may need this test to see if you are at increased risk for heart disease. You may also need this test if you have already had heart problems, such as a heart attack. This test is not used as often as a lipid profile. A lipid profile measures HDL and LDL cholesterol. But some studies suggest that apolipoprotein A test results are a good measure of your heart disease risk.  

This test may also help your healthcare provider fine-tune your risk if you have a family history of heart disease. 

You may also need tests that measure:

• Lipid profile

• LDL cholesterol

• HDL cholesterol

• Triglycerides

• Total cholesterol

• Apolipoprotein B

The accuracy of your heart disease risk is better when both apolipoprotein A and apolipoprotein B levels are measured and looked at together.

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in milligrams per deciliter (mg/dL). For men, the normal range is 110 to 180 mg/dL; for women, the normal range is 110 to 205 mg/dL.

Your apolipoprotein A levels may be high if you:

• Have high levels of apolipoprotein (familial hyperalphalipoproteinemia)

• Have a genetic disorder called familial cholesteryl ester transfer protein deficiency

• Take medicines containing extra estrogens

• Take niacin or statins, a type of cholesterol-lowering medicine

• Take statins

• Lose weight

Your apolipoprotein A levels may be low if you have:

• Low levels of apolipoprotein (familial hypoalphalipoproteinemia)

• Tangier disease, a rare inherited disorder that lowers the amount of HDL

• Hepatocellular disorders, which are certain types of liver problems

• Poorly controlled diabetes

• Nephritic syndrome, a group of kidney problems

• Chronic kidney (renal) failure

• Coronary artery disease. This means the arteries carrying blood to the heart become narrowed and hardened.

• Cholestasis, which means problems with the flow of bile from the liver

Smoking cigarettes, taking diuretics, or taking medicines that contain androgens can also cause lower levels of apolipoprotein A. 

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

Cigarette smoking can affect this test. Certain medicines can also affect your test results. They include:

• Niacin

• Statins

• Diuretics

• Medicines containing estrogens or androgens

Tell your healthcare provider if you smoke or take any medicines regularly, such as statins, diuretics, or hormone medicine. Follow your provider's directions about whether or not you need to stop taking some of these medicines for the test. Tell your healthcare provider about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.