Apolipoprotein A1 (ApoA1) is the primary protein associated with high-density lipoprotein (HDL) particles, and plays a central role in reverse cholesterol transport.
HDL cholesterol (HDL-C) and ApoA1 concentrations are inversely related to the risk for coronary artery disease (CAD).
There are a variable number of ApoA1 proteins per HDL particle. Therefore, ApoA1 is not a 1:1 surrogate marker for HDL particles.
Similarly, the number of ApoA1 proteins and the amount of cholesterol contained in HDL particles is highly variable. This heterogeneity has led to unique clinical findings related to ApoA1 compared with HDL-C.
Reference ranges:
Males:
|
Age |
Apolipoprotein A (mg/dL) |
|
<24 months |
Not established |
|
2-17 years |
Low: <115 Borderline low: 115-120 Acceptable: >120 |
|
>18 years |
> or =120 |
Females:
|
Age |
Apolipoprotein A (mg/dL) |
|
<24 months |
Not established |
|
2-17 years |
Low: <115 Borderline low: 115-120 Acceptable: >120 |
|
>18 years |
> or =140 |
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
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.
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- Low levels of apolipoprotein A1 (ApoA1) confer increased risk of atherosclerotic cardiovascular disease.
- ApoA1 below 25 mg/dL may aid in the detection of a genetic disorder such as Tangier disease.
- ApoA1 is often interpreted as a ratio with apolipoprotein B (ApoB).
- Low concentrations of ApoA1, but not HDL-C, are predictive of preclinical atherosclerosis as assed by computed tomography estimated coronary artery calcium (CAC) scoring.
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
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, or CETP
- Take medicines containing extra estrogens
- Take niacin or statins, a type of cholesterol-lowering medicine
- Take statins
- Lose weight
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- Increased ApoA1 concentrations are more strongly associated with a reduction in risk of a first myocardial infarction than HDL-C concentrations.
- Increased ApoA1, but not HDL-C concentrations, are associated with reduced cardiovascular events among statin-treated patients, even when LDL-C <50 mg/dL.
- In statin-treated patients, patients whose ApoA1 increased while on treatment were at lower risk than those whose ApoA1 did not increase.
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