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Heart health

Apolipoprotein B

Also known as: ApoB blood test, Apolipoprotein B-100 test, Apolipoprotein B-containing lipoprotein test

The Apolipoprotein B (ApoB) test measures the amount of ApoB protein in your blood. ApoB is the main structural protein found in all major atherogenic lipoproteins — particles that carry “bad” cholesterol and can contribute to plaque buildup in arteries. Each atherogenic particle contains one ApoB molecule, meaning ApoB provides a direct count of the number of harmful cholesterol particles in circulation.

ApoB testing helps healthcare providers assess the risk of heart disease more precisely than traditional LDL cholesterol measurements. Even if LDL-C levels appear normal, a high ApoB result can signal elevated heart health risk.

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Key takeaways

  • Sample required: Blood (usually from a vein in the arm; some at-home kits use a finger prick)

  • Tests for: The concentration of ApoB-containing lipoproteins — key markers of heart disease risk.

  • Typical healthy range: <90 mg/dL for low-risk individuals; <80 mg/dL for people at high risk.

What can an ApoB test tell you?

ApoB reflects the total number of cholesterol-carrying lipoprotein particles that can damage blood vessel walls and form arterial plaques. Because it measures particle count rather than cholesterol concentration, it can uncover hidden heart health risks.

Providers use ApoB testing to:

  • Refine heart health risk assessment. ApoB identifies people at higher risk even when LDL appears normal.

  • Guide lipid-lowering therapy. Elevated ApoB may justify more aggressive statin or non-statin therapy.

  • Monitor treatment effectiveness. A falling ApoB level indicates a reduction in atherogenic particle number and heart health risk.

The American Heart Association (AHA) and American College of Cardiology (ACC) recognize ApoB as a valuable marker for improving cardiovascular risk prediction and treatment personalization.

What is being tested?

ApoB is the structural protein found on all atherogenic lipoproteins, including:

  • Low-density lipoprotein (LDL)

  • Very-low-density lipoprotein (VLDL)

  • Intermediate-density lipoprotein (IDL)

  • Lipoprotein(a)

Each of these particles carries one ApoB molecule, so the ApoB test provides a count of total atherogenic (“bad cholesterol”) particles, unlike LDL cholesterol, which measures cholesterol content. 

Elevated ApoB levels indicate an increased number of these harmful particles that can penetrate arterial walls and promote plaque formation, upping your risk for heart disease.

Where is the ApoB test typically included?

The ApoB test is usually ordered as part of advanced lipid testing or when traditional cholesterol results are unclear. It’s typically part of an advanced lipid panel and comprehensive cardiovascular risk panel, which both offer a more detailed look at heart health risks.

Who should get an ApoB test?

ApoB testing is most useful for people whose standard lipid panels may not tell the full story. You may benefit from an ApoB test if you have:

  • Metabolic syndrome (abdominal obesity, high triglycerides, elevated blood pressure)

  • Type 2 diabetes

  • High triglycerides (>200 mg/dL)

  • Obesity or insulin resistance

  • A strong family history of early heart disease

  • Previous heart health issues despite normal LDL cholesterol

Routine ApoB testing can also help assess residual risk in people already taking cholesterol-lowering medications.

How Labs by Hers works

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  • 2

    Get your results

    Review your lab results to understand which areas of your health may need attention.

  • 3

    Spot early signals

    Identify potential health risks or system imbalances before they become more serious.

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    Track your progress through a mid-year panel and ongoing provider check-ins.

Not available in all 50 states. Eligibility and provider order required. Lab results alone are not intended to diagnose, treat, or cure any condition. A provider will reach out about critical results and plans include access to 24/7 provider messaging.

Images for illustrative purposes only.

Frequently asked questions

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What causes changes in ApoB levels?

Apolipoprotein B (ApoB) levels can rise or fall depending on metabolic health, genetics, and liver function. High ApoB is often linked to genetic lipid disorders like familial hypercholesterolemia, as well as type 2 diabetes, insulin resistance, high triglycerides, metabolic syndrome, chronic kidney disease, or a diet high in saturated fat and refined carbohydrates.

Low ApoB levels may occur with malnutrition, hyperthyroidism, liver disease, or the use of certain cholesterol-lowering medications, including statins and PCSK9 inhibitors. Because ApoB reflects the number of atherogenic particles in the blood, changes are typically evaluated alongside cholesterol and triglyceride results to assess cardiovascular risk.

Is fasting required?

No. ApoB testing does not require fasting for accurate results. Still, check with your provider about their recommendations.

How often should ApoB be tested?

There is no established guideline on how often to test ApoB, but a provider may order the test if you have certain heart health risk factors or if they need to monitor your response to treatment for high cholesterol or heart disease.

How is ApoB different from LDL cholesterol?

LDL cholesterol measures the amount of cholesterol inside LDL particles, while ApoB counts the total number of particles capable of causing plaque buildup.

What are optimal ApoB levels?

Under 90 mg/dL is ideal for most adults; under 80 mg/dL is recommended for people at high risk for heart disease.

Does insurance cover ApoB testing?

It may, depending on why it’s being ordered — check with your insurance company or healthcare provider’s office. Insurance is not required for lab testing available through the Hers platform.

What tests are related to this biomarker?

• Lipid Panel (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides)

• Non-HDL cholesterol

• Apolipoprotein A-I (ApoA1)

• Lipoprotein(a)

• High-Sensitivity C-Reactive Protein (hs-CRP)

The information provided here is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk to a qualified healthcare provider about your specific health concerns.

Related biomarkers

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High-Sensitivity C-Reactive Protein

High-Sensitivity C-Reactive Protein (hs-CRP) is a liver-made protein that rises with inflammation. A low level is associated with a lower heart disease risk.

Learn more about High-Sensitivity C-Reactive Protein

Lipoprotein (a)

Lipoprotein (a), or Lp(a), is a genetically inherited cholesterol particle similar to LDL. A low level is a good sign for heart health.

Learn more about Lipoprotein (a)

Non-HDL Cholesterol

Non-HDL cholesterol includes all the "bad" types of cholesterol that can build up in your arteries. A healthy level is a good sign for your overall heart health.

Learn more about Non-HDL Cholesterol

HDL Cholesterol

HDL, or “good” cholesterol, acts like a cleanup crew to clear harmful fats from your blood. A healthy HDL level helps prevent buildup in your arteries.

Learn more about HDL Cholesterol

LDL Cholesterol

LDL is the “bad” cholesterol linked to plaque buildup in artery walls. A healthy level means fewer harmful cholesterol particles in your blood, which reduces overall risk for plaque buildup.

Learn more about LDL Cholesterol

Total Cholesterol

Total cholesterol is the total amount of all cholesterol types, including HDL, LDL, and other blood fats, and gives a general snapshot of your cholesterol status. When the number is in a good range, it shows a lower risk of developing heart disease.

Learn more about Total Cholesterol

Cholesterol/HDL Ratio

This ratio compares your total cholesterol to HDL, the "good" cholesterol.

Learn more about Cholesterol/HDL Ratio

Triglycerides

Triglycerides are a type of fat in your blood made from unused calories that are stored for energy. Low triglyceride levels indicate that your body is not having problems with insulin resistance or processing fat, which is good.

Learn more about Triglycerides

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Reviewed by Darragh O'Carroll, MD

Published 12/04/2025