Apolipoprotein B (ApoB)
ApoB counts the cholesterol-carrying particles that can build up in artery walls, which can add detail beyond your LDL cholesterol number.
AI-drafted. Awaiting verificationAlso called ApoB, Apo B, ApoB-100LOINC 1884-6
Check your result
Type your result to see where it falls.
Nothing you type here leaves your browser.
What it is
Apolipoprotein B (ApoB) is a protein that sits on the surface of the particles in your blood that carry cholesterol and fat, including LDL and VLDL. Each of these particles carries exactly one ApoB, so the ApoB result is a count of the particles. Lipoprotein(a) particles carry one as well. LDL cholesterol, by comparison, measures how much cholesterol is inside the LDL particles. ApoB is often ordered along with a lipid panel, and you don't need to fast for it.
Why it matters
Particles that carry ApoB can slip into artery walls and build up there, so a higher count is linked to more heart attacks and strokes over time. Two people can have the same LDL cholesterol but different ApoB, especially when triglycerides or blood sugar are high or when LDL cholesterol is low. In that case ApoB tends to track risk better. The 2026 US cholesterol guideline says ApoB testing can help refine risk and guide treatment decisions once LDL and non-HDL cholesterol goals have been met.
If it’s low
A low ApoB is usually good news, and it is expected if you take cholesterol-lowering treatment. Very low levels are uncommon without treatment. When they do happen, they can come from rare inherited conditions that change how fats travel in the blood, poor absorption of fat, an overactive thyroid or liver disease. Your clinician can tell you whether it needs a closer look.
Common causes
- Cholesterol-lowering treatment
- A low-fat diet or weight loss
- Rare inherited conditions such as familial hypobetalipoproteinemia
- Poor absorption of fat or malnutrition
- An overactive thyroid
- Severe liver disease
What can help
- Ask your clinician whether the result fits with any treatment you take
- Mention symptoms such as greasy stools, unplanned weight loss or numbness and tingling
If it’s high
A higher ApoB means more cholesterol-carrying particles are circulating. This is common, and it often goes along with higher LDL cholesterol or triglycerides. Many things can raise it, including diet, weight, blood sugar, thyroid and kidney conditions, genetics and some medicines. Your clinician can put your number in the context of your overall heart risk.
Common causes
- A diet high in saturated fat and refined carbohydrates, or weight gain
- Insulin resistance, prediabetes or type 2 diabetes
- High triglycerides
- An underactive thyroid
- Chronic kidney disease or nephrotic syndrome
- Inherited conditions such as familial hypercholesterolemia or familial combined hyperlipidemia
- Some medicines, such as corticosteroids, progestins and anabolic steroids
- Pregnancy and the menopausal transition
What can help
- Eat more fiber-rich foods such as vegetables, beans, oats and fruit, and fewer foods high in saturated fat
- Aim for regular physical activity
- If you carry extra weight, ask your clinician about a plan that fits you
- Ask your clinician whether thyroid, kidney or blood sugar problems should be checked
- Ask your clinician whether any of your medicines could play a role
- Ask how your ApoB fits with your overall risk and whether treatment is worth discussing
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: up to 90 mg/dL. Source: Labcorp, ARUP Laboratories.
- Adults (this one applies)up to 90 mg/dL
Sources: Labcorp, ARUP Laboratories
See ApoB by age and sex, with the U.S. survey numbers where they exist.
Labcorp ApoB reference categories (adults)
- Desirablebelow 90 mg/dL
- Borderline high90 to under 100 mg/dL
- High100 to under 130 mg/dL
- Very high130 and above mg/dL
2026 ACC/AHA apoB goals for selected risk groups (Figure 1)
- Under 55: meets the goal for the highest-risk groupsbelow 55 mg/dL
- 55 to under 70: meets the goal for high-risk groups55 to under 70 mg/dL
- 70 to under 90: meets the goal for lower-risk groups70 to under 90 mg/dL
- 90 or higher: above all three ApoB goals90 and above mg/dL
2019 ESC/EAS ApoB secondary goals by risk group
- Under 65: meets the goal for very high riskbelow 65 mg/dL
- 65 to under 80: meets the goal for high risk65 to under 80 mg/dL
- 80 to under 100: meets the goal for moderate risk80 to under 100 mg/dL
- 100 or higher: above all three ApoB goals100 and above mg/dL
If this applies to you
ApoB means a little more for some people. Open the one that fits you.
High cholesterol or heart risk
ApoB counts plaque-building particles, since each one carries a single ApoB. The 2026 U.S. guideline says ApoB can be useful on treatment once LDL and non-HDL goals are met, especially with diabetes, high triglycerides or heart disease, because LDL and ApoB disagree more often in those cases.
Tracking for long-term health
The 2026 U.S. cholesterol guideline counts a high ApoB as a factor that adds to heart risk, and says ApoB predicts risk better than LDL when the two disagree. For people on cholesterol treatment, it finds ApoB useful once LDL and non-HDL goals are met.
Keto or low-carb eating
ApoB counts the particles that can build plaque. In an observational UK Biobank study, where diet came from 24-hour diet questionnaires, people eating a low-carb, high-fat diet had higher average LDL and ApoB, and very high LDL was nearly twice as common. A study like this can't show that the diet caused the difference.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles 2015-2016. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore ApoB by age and sex: every percentile as a table, with a download.
What can affect your result
- Eating: ApoB changes little after a meal, unlike triglycerides and calculated LDL cholesterol
- Cholesterol-lowering treatment, which lowers ApoB over several weeks
- Diet, weight change and physical activity
- Blood sugar control and triglyceride level
- Thyroid, kidney and liver conditions
- Pregnancy and menopause
- Lab method: results from different labs can differ somewhat
- A very cloudy (lipemic) sample from very high triglycerides can affect some immunoassays; the lab may flag or dilute it.
- Each Lp(a) particle carries one ApoB-100, so a high Lp(a) adds to the total ApoB.
- Assays from different manufacturers can differ a little, so compare results from the same lab when you track changes.
About 4-12 weeks to settle after starting or changing diet or cholesterol-lowering treatment.
When to talk to a clinician
ApoB is not an urgent test. Talk with a clinician soon if your result is above 130 mg/dL (1.3 g/L). Labcorp calls that range very high, and ARUP and the 2018 US cholesterol guideline count 130 mg/dL or more as a factor that raises heart risk. A family history of early heart disease adds to the reason to ask. Mention any result of 90 mg/dL (0.9 g/L) or more at your next routine visit. If you have chest pain, trouble breathing or fainting, call 911 or your local emergency number, whatever your results are.
Questions you could ask
- Is ApoB useful for me, given my triglycerides, blood sugar or family history?
- How often should we repeat my lipid tests?
- How does my ApoB compare with my LDL cholesterol and non-HDL cholesterol?
- What ApoB goal makes sense for my overall heart risk?
- Would checking Lp(a) or other lipid and metabolic markers help explain this?
- Should we recheck it after a few months of lifestyle changes?
Questions people ask
What is the difference between ApoB and LDL cholesterol?
LDL cholesterol measures how much cholesterol is carried inside LDL particles. ApoB counts every particle that can carry cholesterol into artery walls, including LDL, VLDL and Lp(a). When the two disagree, ApoB tends to predict heart risk better. Disagreement is more common with high triglycerides, diabetes or a low LDL cholesterol.
Do I need to fast before an ApoB test?
No. ApoB changes little with eating, so a non-fasting sample works. Follow any fasting instructions for other tests drawn at the same time.
What ApoB level should I aim for?
It depends on your overall heart risk. Labcorp and ARUP list under 90 mg/dL as desirable. The 2026 US guideline suggests goals of under 90, 70 or 55 mg/dL for selected risk groups, and the 2019 European guideline suggests under 100, 80 or 65 mg/dL. Both treat ApoB goals as secondary to LDL cholesterol goals. The European guideline grades its ApoB goals as moderate evidence because they were inferred from LDL cholesterol trials. Your clinician can tell you which group fits you.
How do I convert ApoB from g/L to mg/dL?
Multiply g/L by 100. For example, 0.9 g/L is 90 mg/dL. To go the other way, divide mg/dL by 100.
Show the science and sources
Units
- 1 mg/dL = 1 mg/dL
- 1 mg/dL = 0.01 g/L
Is a change real?
ApoB naturally varies about 6.7% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 19% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: The European Biological Variation Study (EuBIVAS): a summary report.
For clinicians and researchers
ApoB-100 is the structural protein of VLDL, IDL, LDL and Lp(a), with one molecule per particle, so serum ApoB approximates the number of atherogenic particles. ApoB-48 (chylomicrons and their remnants) is under 1% of ApoB-containing particles even after a meal, which is why fasting is not needed; the 2019 ESC/EAS guideline also notes that standardized, automated ApoB methods are available. Labcorp lists an immunologic method and ARUP quantitative immunoturbidimetry. The 2026 ACC/AHA guideline (Guideline-at-a-Glance) says apoB testing can be useful to improve risk assessment and guide therapy once LDL-C and non-HDL-C goals are met, particularly with triglycerides above 200 mg/dL, diabetes or achieved LDL-C under 70 mg/dL. Its Figure 1 sets apoB goals of under 90, 70 or 55 mg/dL for selected risk groups (for example, primary prevention with triglycerides of 150-499 mg/dL, diabetes, subclinical atherosclerosis and clinical ASCVD). The 2018 AHA/ACC guideline listed apoB of 130 mg/dL or more (roughly equivalent to LDL-C of 160 mg/dL or more) as a risk-enhancing factor, and ARUP's interpretive note repeats this. The 2019 ESC/EAS guideline gives secondary apoB goals of under 100, 80 and 65 mg/dL for moderate, high and very high risk, graded moderate because they were defined by inference rather than tested in outcome trials. Molar reporting (nmol/L, LOINC 76482-9) exists but has no standard conversion here, so only mg/dL and g/L are converted.
LOINC 1884-6 (primary), 1871-3, 76482-9. Specimen: serum-or-plasma.
Sources
- Apolipoprotein B (test 167015), Labcorp
- Apolipoprotein B (test 0050029), ARUP Laboratories
- Apolipoprotein B/A Ratio (test 0050028), ARUP Laboratories
- 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia, Journal of the American College of Cardiology / Circulation (2026)
- 2026 Dyslipidemia Guideline-at-a-Glance, Journal of the American College of Cardiology (2026)
- 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk, European Heart Journal (2019)
- 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol, Circulation (2019)
- Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III): Executive Summary, NIH / National Heart, Lung, and Blood Institute (2001)
AI-drafted. Awaiting verification. Last reviewed 2026-10-03. How we build and check these pages.