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Test ID APOA1 Apolipoprotein A1, Serum


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL

Collection Instructions:

1. Centrifuge and aliquot within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.


Useful For

Evaluating risk for atherosclerotic cardiovascular disease

 

Aiding in the detection of Tangier disease

Method Name

Automated Turbidimetric Immunoassay

Reporting Name

Apolipoprotein A1, S

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 8 days
  Frozen  60 days
  Ambient  24 hours

Clinical Information

Apolipoprotein A1 (ApoA1) is the primary protein associated with high-density lipoprotein (HDL) particles, and plays a central role in reverse cholesterol transport.(1) HDL cholesterol (HDL-C) and ApoA1 concentrations are inversely related to the risk for coronary artery disease (CAD).(2) 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.

 

Increased ApoA1 concentrations are more strongly associated with a reduction in risk of a first myocardial infarction than HDL-C concentrations.(3) Low concentrations of ApoA1, but not HDL-C, are predictive of preclinical atherosclerosis as assed by computed tomography estimated coronary artery calcium (CAC) scoring.(4) Increased ApoA1, but not HDL-C concentrations, are associated with reduced cardiovascular events among statin-treated patients, even when LDL-C <50 mg/dL.(5) In statin-treated patients, patients whose ApoA1 increased while on treatment were at lower risk than those whose ApoA1 did not increase.

Reference Values

Males

Age

Apolipoprotein A (mg/dL)

<24 months

Not established

2-17 years

Low: <115

Borderline low: 115-120

Acceptable: >120

>18 years

≥120

 

Females

Age

Apolipoprotein A (mg/dL)

<24 months

Not established

2-17 years

Low: <115

Borderline low: 115-120

Acceptable: >120

>18 years

≥140

Interpretation

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).

Clinical Reference

1. Sorci-Thomas MG, Thomas MJ: Why Targeting HDL Should Work as a Therapeutic Tool, but Has Not. J Cardiovasc. Pharmacol 2013;62:239-246

2. Di Angelantonio E, Sarwar N, Perry P, et al: Emerging Risk Factors Collaboration. Major lipids, apolipoproteins, and risk of vascular disease. JAMA 2009;302:1993-2000

3. McQueen MJ, Hawken S, Wang X, et al: Lipids, lipoproteins, and apolipoproteins as risk markers of myocardial infarction in 52 countries (the INTERHEART study): a case control study. Lancet 2008;372:224-233

4. Sung KC, Wild SH, Byrne CD: Controlling for apolipoprotein A-I concentrations changes the inverse direction of the relationship between high HDL-C concentration and a measure of pre-clinical atherosclerosis. Atherosclerosis 2013;231:181-186

5. Boekholdt SM, Arsenault BJ, Hovingh GK, et.al: Levels and Changes of HDL Cholesterol and Apolipoprotein A-I in Relation to Risk of Cardiovascular Events Among Statin-Treated Patients: A Meta-Analysis. Circulation 2013;128:1504-1512

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Analytic Time

1 day

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

82172

LOINC Code Information

Test ID Test Order Name Order LOINC Value
APOA1 Apolipoprotein A1, S 1869-7

 

Result ID Test Result Name Result LOINC Value
APOA1 Apolipoprotein A1, S 1869-7