Apolipoprotein B
Code:8020
Analysis details
Methodology
- Immunoturbidimetry
Expected Turnaround Time
1 day
Special Instructions
- Observe a minimum 12-hour fast before specimen collection.
- Avoid vigorous physical activity and minimize emotional stress for 30 minutes before the blood draw.
- Do not smoke during the 30 minutes prior to collection.
How to use
The Apolipoprotein B test is used alongside a lipid profile to appraise risk for atherosclerotic cardiovascular disease. When apolipoprotein A1 is ordered concurrently, clinicians may calculate the apoB/apoA1 ratio as an alternative marker of atherogenic balance. Measurement of apoB is informative when triglycerides are increased and calculated LDL cholesterol is less reliable. Serial apoB determinations can be used to track the effect of dietary modification and lipid-lowering therapy on atherogenic lipoprotein burden. Synonyms used in practice include Apo B, Apolipoprotein B-100, and Beta apolipoprotein.
Limitations
Apolipoproteins constitute the protein framework of lipoproteins that ferry lipids through the circulation. Apolipoprotein B is produced as two physiologic isoforms: apoB-100, synthesized in the liver and incorporated into very-low-density lipoproteins that are progressively remodeled to low-density lipoproteins, and apoB-48, synthesized in the intestine and present in chylomicrons that transport dietary lipids to the liver. LDL particles deliver cholesterol to peripheral tissues. Persistent elevation of LDL promotes formation of atheromatous plaque, reduces vascular compliance, and increases the likelihood of myocardial infarction and stroke. The circulating concentration of apoB-100 mirrors the number of atherogenic particles such as LDL and VLDL and may align more closely with atherosclerotic cardiovascular disease risk than the concentration of LDL cholesterol alone.
| Reference interval |
| |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Indications | Assessment for suspected deficiency or overproduction of apolipoprotein B, Individuals with a family history of premature coronary artery disease and/or dyslipidemia, Hypertriglyceridemia that compromises interpretation of calculated LDL cholesterol, Further risk stratification when previous testing suggests high atherosclerotic cardiovascular disease risk, Monitoring response to lipid-lowering medications (e.g., statins) and restriction of saturated animal fats in the diet, Evaluation in the presence of major atherosclerotic cardiovascular disease risk factors (smoking; age thresholds: men ≥45 years and women ≥55 years; blood pressure ≥140/90 mm Hg; family history of premature ASCVD; documented coronary artery disease or a history of myocardial infarction or stroke; diabetes mellitus; obesity; alcohol misuse; diets high in saturated fat; physical inactivity) |
Possible Causes of Abnormal Results
Increased levels
- anabolic steroids
- androgens
- diet high in saturated fat and cholesterol
- diuretics
- obesity
- physical inactivity
- pregnancy
- smoking
Decreased levels
- diet low in cholesterol and saturated fat and high in polyunsaturated fatty acids
- estrogens
- fibrates
- intensive physical exercise
- oral contraceptives
- phenobarbital
- prolonged fasting
- statins
- thyroxine
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |