Apolipoprotein B (ApoB) is the major structural protein of atherogenic lipoproteins, including:

• LDL

• VLDL

• IDL

• Lipoprotein(a)

Each atherogenic particle contains one ApoB molecule, so ApoB reflects the number of atherogenic particles, not just cholesterol content.

Normal Reference Range

• Desirable level: < 90 mg/dL

• High cardiovascular risk: > 130 mg/dL

(Reference ranges may vary slightly by lab.)

Clinical Significance

1️⃣ Strong Predictor of Cardiovascular Disease (CVD)

ApoB represents total atherogenic particle number.

High ApoB is associated with:

• Coronary artery disease (CAD)

• Myocardial infarction

• Stroke

• Peripheral vascular disease

It may predict risk better than LDL-C in some patients.

2️⃣ Identifies “Hidden Risk”

Two patients may have:

• Same LDL-C

• Different ApoB levels

Higher ApoB = more LDL particles = higher risk

Especially useful in:

• Diabetes mellitus

• Metabolic syndrome

• Hypertriglyceridemia

• Obesity

3️⃣ ApoB/ApoA1 Ratio

This ratio reflects balance between:

• Atherogenic particles (ApoB)

• Protective HDL particles (ApoA1)

High ratio → High cardiovascular risk

Considered one of the strongest lipid-related predictors of CVD.

4️⃣ Familial Hyperlipidemia

Elevated ApoB seen in:

• Familial hypercholesterolemia

• Familial combined hyperlipidemia

Helps in diagnosis and monitoring.

5️⃣ Monitoring Lipid-Lowering Therapy

ApoB is useful in:

• Assessing statin response

• Evaluating residual cardiovascular risk

Target levels often recommended in high-risk patients.

6️⃣ Metabolic Syndrome

Typical pattern:

• ↑ Triglycerides

• ↓ HDL

• ↑ Small dense LDL

• ↑ ApoB

Indicates increased atherogenic particle burden.