Apolipoprotein A-I (apo A-I) is a protein that has a specific role in the metabolism of lipids and is the main protein component in high-density lipoprotein (HDL, the “good cholesterol”). This test measures the amount of apo A-I in the blood.
To determine whether or not you have an adequate level of apo A-I, especially if you have a low level of high-density lipoprotein (HDL-C), and to help determine your risk of developing cardiovascular disease (CVD). this test measures the amount of apolipoprotein A in your blood. Apolipoprotein A is a protein carried in HDL (“good”) cholesterol. It helps to start the process for HDL to remove bad types of cholesterol from your body.
Apolipoprotein A-I (apo A-I) may be ordered, along with other lipid tests, as part of a profile to help determine a person’s risk of developing cardiovascular disease (CVD). It may be used as an alternative to high-density lipoprotein (HDL) test, but it is not generally considered “better” or more informative than HDL and is not ordered routinely. An apo A-I test may sometimes be ordered to:
- Help diagnose inherited or acquired conditions that cause apo A-I deficiencies
- Help evaluate people who have a personal or family history of heart disease and/or high cholesterol and triglycerides
- Monitor the effectiveness of lifestyle changes and lipid treatments
An apo A-I may be ordered along with an apolipoprotein B (apo B) test to determine an apo B/apo A-I ratio. This ratio is sometimes used as an alternative to a total cholesterol/HDL ratio (sometimes reported as part of a lipid profile) to evaluate the risk for developing CVD.
Apolipoproteins are proteins that bind lipids (oil-soluble substances such as fat and cholesterol) to form lipoproteins. They transport the lipids through the lymphatic and circulatory systems. Low levels of apo A-I are associated with low levels of HDL and impaired clearance of excess cholesterol from the body. Low levels of apo A-I, along with high concentrations of apo B, are associated with an increased risk of cardiovascular disease.