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Test Code APOAB Apolipoprotein A1 and B, Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot 1 mL of serum.


Useful For

Assessment of cardiovascular risk

 

Follow-up studies in individuals with basic lipid measures inconsistent with risk factors or clinical presentation

 

Definitive studies of cardiac risk factors in individuals with significant family histories of coronary artery disease or other increased risk factors

Profile Information

Test ID Reporting Name Available Separately Always Performed
RBAA1 Apolipoprotein B/A1 ratio No Yes
APOA1 Apolipoprotein A1, S Yes Yes
APOLB Apolipoprotein B, S Yes Yes

Method Name

Automated Turbidimetric Immunoassay

Reporting Name

Apolipoprotein A1 and B, 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

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus Reject

Clinical Information

Apolipoprotein B (ApoB) is the primary protein component of low-density lipoprotein (LDL). Apolipoprotein A1 (ApoA1) is the primary protein component of high-density lipoprotein (HDL). Elevated ApoB and decreased ApoA1 are associated with increased risk of cardiovascular disease. Multiple studies have reported that ApoB and ApoA1 are more strongly associated with cardiovascular disease than the corresponding lipoprotein cholesterol fraction (see APOA1 / Apolipoprotein A1, Serum and APOLB / Apolipoprotein B, Serum).

 

ApoB is present in all atherogenic lipoproteins including LDL, Lp(a), intermediate-density lipoprotein (IDL), and very low-density lipoprotein (VLDL) remnants. ApoA1 is the nucleating protein around which HDL forms during reverse cholesterol transport. The ApoB:ApoA1 ratio represents the balance between atherogenic and antiatherogenic lipoproteins. Several large prospective studies have shown that the ApoB:ApoA1 ratio performs as well, and often better, than traditional lipids as an indicator of risk.(1-3)

Reference Values

Males

Age

Apolipoprotein A (mg/dL)

Apolipoprotein B (mg/dL)

Apolipoprotein B/A1 ratio

<24 months

Not established

Not established

Not established

2-17 years

Low: <115

Borderline low: 115-120

Acceptable: >120

Acceptable: <90

Borderline high: 90-109

High: ≥110

<0.8

>18 years

≥120

Desirable: <90

Above Desirable: 90-99

Borderline high: 100-119

High: 120-139

Very high: ≥140

 

Lower Risk: <0.7

Average Risk: 0.7-0.9

Higher Risk: >0.9

Females

Age

Apolipoprotein A (mg/dL)

Apolipoprotein B (mg/dL)

Apolipoprotein B/A1 ratio

<24 months

Not established

Not established

Not established

2-17 years

Low: <115

Borderline low: 115-120

Acceptable: >120

Acceptable: <90

Borderline high: 90-109

High: ≥110

<0.8

>18 years

≥140

Desirable: <90

Above Desirable: 90-99

Borderline high: 100-119

High: 120-139

Very high: ≥140

 

Lower Risk: <0.6

Average Risk: 0.6-0.8

Higher Risk: >0.8

Interpretation

Elevated apolipoprotein B (ApoB) confers increased risk of atherosclerotic cardiovascular disease, even in a context of acceptable LDL cholesterol concentrations.

 

Extremely low values of ApoB (<48 mg/dL) are related to malabsorption of food lipids and can lead to polyneuropathy.

 

Reduced apolipoprotein A1 (ApoA1) confers an increased risk of coronary artery disease. Extremely low ApoA1 (<20 mg/dL) is suggestive of liver disease or a genetic disorder.

 

Elevated ApoB:ApoA1 ratio confers increased risk of atherosclerotic cardiovascular disease, independently of LDL and HDL cholesterol concentrations.

Cautions

In very rare cases, gammopathy, in particular type IgM (Waldenstrom macroglobulinemia), may cause unreliable results.

Day(s) Performed

APOA1: Monday through Sunday

APOLB: Monday through Saturday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US 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 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
APOAB Apolipoprotein A1 and B, S 55724-9

 

Result ID Test Result Name Result LOINC Value
APOLB Apolipoprotein B, S 1884-6
APOA1 Apolipoprotein A1, S 1869-7
RBAA1 Apolipoprotein B/A1 ratio 1874-7

Forms

If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen.