When do you test for Apolipoprotein B (Apo B)?

From the Guidelines

Apo B testing is recommended in specific situations, such as when triglyceride levels are persistently elevated above 200 mg/dL, as it may provide a more accurate assessment of cardiovascular risk, as stated in the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol 1. When to test for Apo B is a crucial decision in clinical practice, and the following situations are considered appropriate:

• When LDL cholesterol levels are normal but triglycerides are high
• In patients with metabolic syndrome or diabetes
• For individuals with a strong family history of premature cardiovascular disease
• When considering more aggressive lipid-lowering therapy The test is usually a simple blood draw, requiring no special preparation, although fasting for 9-12 hours before the test may be recommended for more accurate results, as suggested by the 2018 cholesterol clinical practice guidelines: synopsis of the 2018 American Heart Association/American College of Cardiology/Multisociety Cholesterol Guideline 1. Apo B provides a direct measure of the number of atherogenic particles in the blood, offering a more precise assessment of cardiovascular risk than LDL cholesterol alone, as each atherogenic lipoprotein particle contains one Apo B molecule, making it a reliable indicator of the total number of potentially harmful particles, as noted in the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol 1. Understanding Apo B levels can help guide treatment decisions, particularly in determining the intensity of lipid-lowering therapy needed, with normal Apo B levels generally considered to be less than 100 mg/dL, but target levels may be lower for high-risk individuals, as stated in the 2018 cholesterol clinical practice guidelines: synopsis of the 2018 American Heart Association/American College of Cardiology/Multisociety Cholesterol Guideline 1. It is essential to consider the measurement of Apo B in certain circumstances, particularly in patients with hypertriglyceridemia, as it may have advantages, as reported in the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol 1. In clinical practice, the decision to test for Apo B should be based on the individual patient's risk factors and clinical presentation, taking into account the potential benefits and limitations of the test, as discussed in the 2018 cholesterol clinical practice guidelines: synopsis of the 2018 American Heart Association/American College of Cardiology/Multisociety Cholesterol Guideline 1.

From the Research

When to Test for Apolipoprotein B (Apo B)

• Apo B testing can be used to assess cardiovascular risk and guide lipid-lowering therapy, particularly in individuals with mild-to-moderate hypertriglyceridemia, diabetes, obesity, or metabolic syndrome, or very low LDL cholesterol < 70 mg/dL 2.
• Apo B measurement can be used in conjunction with a standard lipoprotein lipid profile to diagnose distinct lipoprotein phenotypes and inform clinical prognosis and care 3.
• The addition of apo B measurement to the routine lipid panel can enhance patient management and is considered a logical next step to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII) and other guidelines 4.
• Apo B can be used to estimate cardiovascular risk and guide therapy, and evidence suggests that it is superior to LDL-C in recognizing those at increased risk of vascular disease and judging the adequacy of lipid-lowering therapy 5.
• Apo B and non-HDL-C are not interchangeable, and apo B is a more direct measure of the number of circulating atherogenic lipoproteins, making it a valuable tool for diagnosis and cardiovascular risk management 6.

Clinical Considerations

• Discordance between levels of LDL-C and apo B, or LDL-C and non-HDL-C, can occur, and atherosclerotic cardiovascular disease risk generally aligns better with apo B or non-HDL-C 2, 3.
• Apo B testing can identify elevated numbers of small cholesterol-depleted LDL particles that are not reflected by LDL and non-HDL cholesterol, making it a useful tool for assessing residual cardiovascular risk 2.
• The use of apo B as a secondary target in patients with specific clinical characteristics, such as mild-to-moderate hypertriglyceridemia or very low LDL cholesterol, can help to reduce residual cardiovascular risk 2, 3.