A standard cholesterol test tells you how much cholesterol is being carried in your blood. What it does not show directly is the number of atherogenic lipoprotein particles carrying that cholesterol. That is what an apolipoprotein B test, usually shortened to ApoB, helps estimate. ApoB can add useful information to a standard cholesterol result, particularly when LDL cholesterol, non-HDL cholesterol and a person's overall cardiovascular risk do not seem to match, yet it is rarely part of a routine NHS cholesterol check. This article explains what ApoB is, how it differs from ordinary cholesterol testing, when it may be useful, and what a high result can mean.
Key points
ApoB is a protein present on atherogenic lipoprotein particles, including LDL, VLDL remnants and Lp(a).
ApoB helps estimate the number of these particles, while LDL cholesterol and non-HDL cholesterol measure the amount of cholesterol they carry.
ApoB is not part of the routine NICE lipid pathway, which usually relies on QRISK, a full lipid profile, non-HDL cholesterol, LDL cholesterol and overall cardiovascular risk assessment.
ApoB may be most useful when standard cholesterol results and overall cardiovascular risk do not seem to match, such as in people with high triglycerides, type 2 diabetes, obesity or metabolic syndrome.
Unlike Lp(a), ApoB-containing lipoproteins can usually be lowered with lipid-lowering treatment and may also improve with changes in diet, weight and activity.
In one sentence: ApoB estimates the number of cholesterol-carrying particles that can contribute to artery disease, and it may be most useful when standard cholesterol results do not fully explain a person's cardiovascular risk.
UK clinical context: ApoB is not part of the standard full lipid profile defined by NICE. UK cardiovascular risk assessment usually relies on QRISK, total and HDL cholesterol, non-HDL and LDL cholesterol, triglycerides, blood pressure, diabetes status, smoking status, kidney disease, family history and clinical judgement.
What is apolipoprotein B (ApoB)?
Cholesterol does not travel through your blood on its own. It is carried inside particles, and the ones that can build up in your arteries each have a single molecule of apolipoprotein B wrapped around them. These are called atherogenic particles, meaning they can contribute to plaque build-up in artery walls, and they include LDL (the so-called bad cholesterol), some related particles such as VLDL remnants, and Lp(a). Because there is just one ApoB molecule per particle, measuring ApoB gives a good estimate of the total number of these particles in your blood.
That distinction matters because cholesterol and other fats enter artery walls inside lipoprotein particles. ApoB-containing particles are involved in plaque formation, and ApoB gives an estimate of how many of these atherogenic particles are circulating. LDL cholesterol and non-HDL cholesterol remain important measures, but they describe the amount of cholesterol carried in the blood rather than the number of particles carrying it. When these measures disagree, ApoB may give useful extra information about cardiovascular risk, as set out in a narrative review in JAMA Cardiology.
ApoB versus LDL cholesterol: what is the difference?
A normal cholesterol test reports your LDL cholesterol, which is the weight of cholesterol packed inside your LDL particles. The catch is that particles are not all the same size. Two people can have the same LDL cholesterol number while one is carrying far more particles, each a little emptier, than the other. The person with more particles may carry more risk, and their LDL result does not show it.
ApoB gets at this by reflecting the number of particles directly. When your LDL cholesterol and your ApoB disagree, which happens in a meaningful number of people, ApoB often tracks cardiovascular risk more closely than LDL cholesterol alone. That gap is why someone can have a reassuring LDL result and still carry a raised particle count underneath it.
Why ApoB matters
For years, cholesterol lowering focused mainly on LDL cholesterol. It works well and remains central to care, but it does not capture everyone's risk on its own. This is where ApoB can help. It is most useful when it adds something beyond the standard lipid measures, particularly in people with high triglycerides, type 2 diabetes, obesity or metabolic syndrome, or where LDL cholesterol and overall risk do not line up. In these situations the blood tends to carry many small, cholesterol-poor particles, so LDL cholesterol can look modest while the particle count, and the risk, is higher.
It is worth being clear that a standard UK cholesterol panel already includes non-HDL cholesterol, which captures the cholesterol in all these particles and is a good everyday measure recommended by NICE. ApoB adds to that by reflecting the particle number itself, which is where it earns its place when the two might disagree.
What the guidelines say
The 2026 ACC/AHA dyslipidemia guideline, a major US guideline, gives ApoB a more explicit role than before. It supports selective ApoB measurement to improve risk assessment and guide treatment, rather than recommending it for everyone. This is most useful where the standard results and overall risk do not seem to match, such as in people with high triglycerides, diabetes or metabolic risk factors, or once LDL and non-HDL cholesterol goals are met. A practical advantage is that ApoB is measured directly rather than calculated, and it does not usually need a fasting sample.
European guidance from the European Society of Cardiology and European Atherosclerosis Society includes ApoB as a secondary treatment target, particularly for people at higher cardiovascular risk. That position carried through into a 2025 focused update of the same guidance.
In the UK, the main heart-risk guideline, NICE NG238, works from your total and HDL cholesterol, non-HDL cholesterol and LDL cholesterol rather than ApoB. So ApoB is not routinely included in NICE-based lipid testing, and it usually needs to be requested separately or arranged through a specialist or private service. This reflects the current NICE-based approach to cardiovascular risk assessment and lipid management.
Who should consider an ApoB test?
ApoB is not something everyone needs. It earns its place most in these situations:
| Situation | Why it matters |
|---|---|
| Type 2 diabetes, prediabetes or metabolic syndrome | These raise the number of harmful particles, which ApoB captures better than LDL |
| High triglycerides | When triglycerides are up, LDL can understate your risk and ApoB is more reliable |
| Heart disease despite a normal cholesterol result | ApoB may reveal a particle burden the standard cholesterol result does not fully capture |
| A strong family history of early heart disease, or suspected familial hypercholesterolaemia | ApoB can add context, but this assessment still depends on LDL cholesterol, family history, examination findings and, where appropriate, specialist assessment or genetic testing |
| Already on treatment and want to check residual risk | Once LDL is at goal, ApoB can show whether the particle burden is truly under control |
Who probably does not need this test
Many people do not need an ApoB test. If your standard cholesterol results, blood pressure, diabetes status, smoking status and overall risk score (such as QRISK) already give a clear picture, ApoB may not change what you or your doctor decide to do. It is most useful when the standard results and the overall risk picture do not seem to match.
Understanding your result: what is a normal or good ApoB level?
ApoB is usually reported in grams per litre (g/L) in the UK, and sometimes in milligrams per decilitre (mg/dL). Risk rises steadily as the number climbs, so it is better to think of it as a spectrum than a simple pass or fail. Your ideal level depends on your overall heart risk, and lower is generally better.
The figures below are common risk-based treatment targets used in European guidance rather than a single normal range, so read them against your own risk and your laboratory's reference range:
| Your cardiovascular risk | Common ApoB treatment target used in European guidance |
|---|---|
| Moderate risk | Below 1.00 g/L (100 mg/dL) |
| High risk | Below 0.80 g/L (80 mg/dL) |
| Very high risk | Below 0.65 g/L (65 mg/dL) |
These are European (ESC/EAS) risk-based ApoB targets, not current NICE treatment thresholds. In UK NHS practice, treatment decisions are usually guided by QRISK, LDL cholesterol, non-HDL cholesterol, clinical history and shared decision-making. There is no single "normal" ApoB that applies to everyone: rather than one universal cut-off, your target drops as your overall cardiovascular risk rises, which is why the risk-based figures above matter more than any single number.
To move between the units, you can roughly divide the mg/dL figure by 100 to get g/L, so 90 mg/dL is about 0.90 g/L. It is best to read your own result against the reference range your laboratory prints alongside it, since methods vary slightly. A raised ApoB does not mean a heart attack is around the corner. It is a signal to look at your overall risk and act on the parts you can change.
A few things other than your usual risk can push ApoB up for a while, including pregnancy, an underactive thyroid, and kidney problems such as nephrotic syndrome. If any of those apply, your doctor will take them into account when reading the result.
How to lower your ApoB
This is the part that sets ApoB apart from an inherited marker like Lp(a), which barely moves whatever you do. ApoB-containing lipoproteins can be lowered. Both treatment and lifestyle can bring them down, because they reduce the number of harmful particles your body makes and clears.
On the lifestyle side, the changes that help most are:
Cutting down on saturated fat, found in fatty and processed meats, butter and many baked goods
Eating fewer refined carbohydrates and added sugars, which drive up particle production, especially if you are insulin resistant
Losing excess weight, which lowers particle numbers noticeably in many people
Being physically active most days
Eating more soluble fibre (oats, beans, pulses) and more oily fish
Lifestyle changes can make a real difference, but they are not always enough on their own, and for many higher-risk people medication is the bigger lever. The medicines used to lower LDL cholesterol also lower ApoB. Statins are the mainstay, and NICE recommends them as the main treatment for reducing cardiovascular risk. If more is needed, ezetimibe and, for higher-risk people, PCSK9 inhibitors lower ApoB further. Therapies that lower ApoB-containing lipoproteins, including statins, ezetimibe and PCSK9 inhibitors, reduce cardiovascular events. Because ApoB reflects particle number so closely, it can be a useful additional way to check whether your particle burden has fallen.
If you would like to understand the inherited side of your heart risk, which lifestyle cannot shift, our companion guide to the Lp(a) blood test covers a marker that works alongside ApoB.
When to see your GP
Speak to your GP if you have a personal or family history of early heart attack or stroke, if you have diabetes or high triglycerides, or if you have a raised ApoB or cholesterol result you would like reviewed. If you already have a high ApoB from a private test, take it to your GP so it can be weighed up alongside your blood pressure, your other cholesterol numbers and your overall risk. Private testing is meant to sit alongside NHS care, not replace it.
Call 999 straight away if you have symptoms of a heart attack or stroke, such as chest pain or tightness, sudden weakness or numbness, a drooping face, slurred speech, severe breathlessness or a collapse. These need urgent help right away, so do not wait for a blood test result.
Common questions about the ApoB blood test
What is ApoB? Apolipoprotein B is a protein found on atherogenic lipoprotein particles, which can contribute to plaque build-up in arteries, with one molecule per particle. Measuring it estimates the number of those particles in your blood, rather than just the cholesterol they contain.
What is a normal or good ApoB level? There is no single official cut-off, and lower is generally better. Risk-based targets used in European guidance are often below 1.00 g/L (100 mg/dL) at moderate risk, below 0.80 g/L (80 mg/dL) at high risk, and below 0.65 g/L (65 mg/dL) at very high risk. These are European (ESC/EAS) targets rather than NICE thresholds, so read your own result against your laboratory's reference range and your overall risk.
What does a high ApoB mean? It means you are carrying a lot of atherogenic particles, which raises your long-term risk of heart attack and stroke. It is a prompt to look at your LDL cholesterol, blood pressure, weight, blood sugar and family history, and to act on what you can change.
What is the difference between ApoB and LDL cholesterol? LDL cholesterol measures the weight of cholesterol inside your LDL particles. ApoB reflects the number of particles themselves. When the two disagree, ApoB often tracks cardiovascular risk more closely.
How can I lower my ApoB naturally? Cutting saturated fat and refined carbohydrates, losing excess weight, staying active, and eating more soluble fibre and oily fish all help. Unlike some inherited markers, ApoB-containing lipoproteins respond to these changes. For many higher-risk people, statins or other lipid-lowering treatment are also needed, so it is worth discussing with your GP.
What is the difference between ApoB and Lp(a)? They answer different questions. ApoB reflects your total atherogenic particles and can be improved with treatment and lifestyle. Lp(a) is a specific inherited particle that is largely fixed for life. Many people benefit from knowing both, and you can read more in our Lp(a) guide.
What is the ApoB to ApoA1 ratio? ApoA1 is the main protein on protective HDL particles. The ApoB to ApoA1 ratio compares harmful particles against protective ones, and a lower ratio is generally better. Some labs report it, but a straightforward ApoB level is enough for most people.
Testing your ApoB with Brooksby Medical
The section below is about our private service, separate from the medical information above.
Brooksby Medical offers a standalone apolipoprotein B (ApoB) test, or you can measure it as part of our Advanced Cholesterol Profile, which looks at ApoB alongside Lp(a) and the standard cholesterol markers. Both come with a written interpretation from a practising GP. This is a paid private service and is not a replacement for NHS cardiovascular care, but it can give you and your GP more information to work with.
References
National Institute for Health and Care Excellence. Cardiovascular disease: risk assessment and reduction, including lipid modification (NG238). 2023. https://www.nice.org.uk/guidance/ng238
Blumenthal RS, Morris PB, Gaudino M, et al. 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia. Circulation. 2026;153:e1154-e1276. doi:10.1161/CIR.0000000000001423. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001423
Sniderman AD, Thanassoulis G, Glavinovic T, et al. Apolipoprotein B Particles and Cardiovascular Disease: A Narrative Review. JAMA Cardiol. 2019;4(12):1287-1295. doi:10.1001/jamacardio.2019.3780. https://pubmed.ncbi.nlm.nih.gov/31642874/
Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111-188. doi:10.1093/eurheartj/ehz455. https://doi.org/10.1093/eurheartj/ehz455
Mach F, Koskinas KC, Roeters van Lennep JE, et al. 2025 Focused Update of the 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J. 2025;46(42):4359-4378. doi:10.1093/eurheartj/ehaf190. https://doi.org/10.1093/eurheartj/ehaf190
Khan SU, Khan MU, Valavoor S, et al. Association of lowering apolipoprotein B with cardiovascular outcomes across various lipid-lowering therapies: systematic review and meta-analysis of trials. Eur J Prev Cardiol. 2020;27(12):1255-1268. doi:10.1177/2047487319871733. https://pubmed.ncbi.nlm.nih.gov/31475865/
Medical disclaimer. This article is for informational purposes and does not constitute medical advice. Blood test results should always be interpreted by a qualified healthcare professional in the context of your individual symptoms, history, and clinical picture. If you have concerns about your health, please consult your GP.