Learning Center › Topic 2 of 6
ApoB: counting the particles that carry cholesterol
LDL-C tells you how much cholesterol is being carried. ApoB reflects how many particles are doing the carrying, and the two numbers don't always match.
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Text description of this 3D model
Two transparent vessel segments, one above the other. Vessel A carries 5 large gold particles; vessel B carries 14 smaller gold particles. Both carry a similar total amount of cholesterol. Each particle wears a teal ring for its single ApoB protein. In the 'Count the carriers' view the rings glow and labels read 'ApoB count: 5' and 'ApoB count: 14'.
Vessels A and B carry a similar total amount of cholesterol (gold), so their LDL-C could look similar. Vessel B packs it into many smaller particles.
Each particle carries exactly one ApoB protein (glowing teal ring). Count them: B has nearly three times as many particles as A. An ApoB test reflects this particle number.
What to know
- ApoB (apolipoprotein B) is a protein found on LDL, VLDL, IDL and Lp(a), the particles that can enter artery walls and contribute to plaque.
- Each of these particles carries one ApoB molecule, so your ApoB level reflects how many potentially plaque-forming particles are circulating.
- LDL-C and ApoB can disagree (called discordance). This is more common with high triglycerides, diabetes, metabolic syndrome or excess weight.
- The 2018 AHA/ACC cholesterol guideline lists an elevated ApoB as a “risk-enhancing factor” that clinicians may consider in some situations.
What this test can do
- Estimate the number of atherogenic (plaque-forming) particles
- Add information when LDL-C and triglycerides don't line up
- Be tracked over time
What it can't do on its own
- Replace a full lipid panel
- Measure Lp(a) specifically
- Diagnose heart disease
Questions to bring to your clinician
- “Could my LDL-C be underestimating my particle number?”
- “Would an ApoB test change how we look at my risk?”
- “Should Lp(a) be measured at the same time?”
Want to Explore Your Cholesterol-Related Risk Markers?
A-List's Hidden Heart Risk Duo measures ApoB and Lp(a) together. It does not include a standard lipid panel, so check the Heart Panels page if you'd also like LDL-C, HDL-C and triglycerides.
“Book This Panel” opens the secure Stan Store checkout for the Hidden Heart Risk Duo: ApoB + Lp(a) ($179), where you choose your appointment time and review the total before paying.
Panels that include this test
- Hidden Heart Risk Duo: ApoB + Lp(a)$179
Every listed panel price includes the required lab order, standard mobile blood collection, collection supplies, and laboratory testing/processing. Only optional upgrades you select (such as the $60 Vein Finder) cost extra. You'll review your selections and final total in Stan Store before paying.
Understand Your Heart Numbers. Keep the Free Guide.
Get our free Heart Numbers Guide, including explanations of common cholesterol-related markers, a tracker for your results, and questions to discuss with your healthcare provider.
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Educational only. This page explains what a test measures. It does not interpret individual results, diagnose a condition, or recommend treatment. A qualified healthcare professional can help decide which tests make sense for you and what your results mean. Do not change medicines or preparation instructions based on this page.
Sources: AHA: Apolipoprotein B · American Heart Association: How to get your cholesterol tested