Apo A-1, apolipoprotein a-1
This test measures the amount of apolipoprotein A in your blood. It helps evaluates your risk for cardiovascular disease.
Apolipoprotein A is a protein carried in HDL ("good") cholesterol. It helps activate the process for HDL to remove bad types of cholesterol from your body. In this way, apolipoprotein A can help to reduce your cardiovascular risk. Although apolipoprotein A levels can be measured, it's more common to measure the HDL and LDL ("bad") cholesterol when looking at cardiovascular risk.
You may have this test to see if you are at increased risk for heart disease. This test is not used as commonly as a lipid profile, which measures HDL and LDL cholesterol. But some studies suggest that apolipoprotein test results can tell your heart disease risk at least as well as a lipid profile.
This test may also help your doctor fine-tune your risk if you have a family history of heart disease.
Your doctor may also order tests that measure:
The accuracy of your heart disease risk improves when both apolipoprotein A and apolipoprotein B levels are measured and looked at together.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Results are given in milligrams per deciliter (mg/dL). A normal level is greater than 120 mg/dL.
Your apolipoprotein A levels may be high if you:
Have familial hyperalphalipoproteinemia
Have a genetic disorder called familial cholesteryl ester transfer protein deficiency, or CETP
Take medications containing excess estrogens
Take statins, a type of cholesterol-lowering medication
Your apolipoprotein A levels may be low if you have:
Chronic renal failure
Coronary artery disease
Smoking cigarettes, taking diuretics, or taking medications that contain androgens can also cause lower levels of apolipoprotein A.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Cigarette smoking can affect this test. Certain medications can also affect your test results, including:
Medications containing estrogens
Medications containing androgens
Tell your health care provider if you smoke or take any medications regularly, such as statins, diuretics, or hormone medication. You may need to stop taking some of these medications for the test. In addition to these drugs, be sure your doctor knows about all other medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.