ApoB
Apolipoprotein B – atherogenic lipoprotein particle count
Also known as
Definition
ApoB is the structural protein of all atherogenic lipoproteins (LDL, VLDL, IDL, Lp(a)) and represents the total number of particles capable of causing atherosclerosis. It is a superior risk marker versus LDL cholesterol because each particle can damage the arterial wall regardless of its cholesterol content. The 2019 ESC/EAS dyslipidaemia guideline lists ApoB testing in individuals with elevated cardiovascular risk.
| Parameter | Value |
|---|---|
| Unit | mg/dl (g/l) |
| Reference Range | Labs state different assessment ranges for ApoB; the range on your own report is what counts, and your doctor interprets the result. Target values that guidelines give according to cardiovascular risk are not reference ranges. |
Agree on your personal target range with your doctor.
US and European labs report ApoB in mg/dl; internationally also g/l (1 g/l = 100 mg/dl). ESC cutoffs are expressed in mg/dl.
↓ What a low value means
Low ApoB values mean few atherogenic particles and are associated with lower cardiovascular risk. Extremely low levels may indicate hypobetalipoproteinemia, malabsorption, or severe malnutrition. A clinically relevant deficiency is rare with normal eating.
↑ What a high value means
Elevated ApoB reflects a high number of atherogenic particles and is a stronger predictor of cardiovascular events than LDL cholesterol alone. Causes include genetic hypercholesterolemia, insulin resistance, type 2 diabetes, metabolic syndrome, hypothyroidism, and kidney disease. ApoB can be elevated even with normal LDL cholesterol (discordance phenomenon with small dense LDL particles). The 2019 ESC/EAS guideline names ApoB as a secondary treatment goal, for example below 100 mg/dl at moderate and below 80 mg/dl at high risk. Whether treatment is given and which of these goals applies is decided by your doctor based on overall risk; they are not normal or reference values.
✓ What can influence this value
ApoB is influenced by diet (saturated fats and trans fats can raise the value, soluble fiber and a Mediterranean diet can lower it), physical activity, body weight, and insulin resistance. Genetic factors, thyroid and kidney diseases, and lipid-lowering medications such as statins, ezetimibe, or PCSK9 inhibitors also act on the value. The assessment is made by the treating doctor.
When to test
ApoB is mainly measured with a family history of cardiovascular disease, with risk factors, with known elevated LDL, and during lipid-lowering therapy. Fasting is not strictly required; consistent sampling conditions improve comparability. How often it is measured is decided by your doctor.
Frequently asked questions
Why is ApoB more informative than LDL cholesterol? +
LDL cholesterol measures the cholesterol content in LDL particles, not their number. ApoB directly reflects particle count. With small dense LDL particles, LDL cholesterol can be normal while ApoB is elevated — the discordance phenomenon, which underestimates true cardiovascular risk.
Does diet affect ApoB? +
Yes. A Mediterranean diet, less saturated fat, more soluble fiber, and weight loss are associated with lower ApoB values. With familial hypercholesterolemia, the effect of diet alone is often limited.
When is ApoB more informative than the LDL value? +
In people with elevated triglycerides, insulin resistance, type 2 diabetes, or when LDL calculated by the Friedewald equation is unreliable. The ESC/EAS guideline lists ApoB as an alternative or supplementary parameter in people at elevated cardiovascular risk.
ApoB
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.