Apolipoprotein B Test

What is Apolipoprotein B?

Apolipoproteins (Apo) are special proteins that attach to lipids (fats), forming lipoproteins. Lipoproteins enable the transport of fats such as cholesterol and triglycerides in the blood. Apolipoprotein B (ApoB) is one of the principal types of Apo.

ApoB (ApoB-100) is the main protein of potentially harmful lipoprotein types, including Low-Density Lipoprotein (LDL, known as the “bad” cholesterol), Very Low-Density Lipoprotein (VLDL), Intermediate-Density Lipoprotein (IDL), and Lipoprotein(a). A different form of Apo B (ApoB-48) is the main Apo of chylomicrons – lipoproteins that transport dietary triglycerides (also fats) in the blood from the gut to the tissues.

What is an Apolipoprotein B test?

The ApoB test measures the major protein in LDL, VLDL, IDL, and Lipoprotein(a). High levels of ApoB indicate a greater risk of cardiovascular disease (CVD; heart and blood vessel disease). This is because Apo B carries the components in blood that make up the waxy fat or plaque that can block the arteries, leading to heart attack and/or stroke.

The ApoB test can be more exact than a lipid panel test that focuses on LDL-cholesterol, because it measures only the cholesterol within LDL particles. The exactness of the ApoB test is because each lipoprotein particle contains one ApoB molecule, providing an exact number of plaque-forming lipoprotein particles. ApoB captures all potentially dangerous particles, those being LDL, VLDL, IDL, and lipoprotein(a).

The clinical importance is that rather than how much cholesterol is in the blood, ApoB represents the number of lipoprotein particles that can get trapped in arterial walls and form plaques. One person may have a similar LDL-cholesterol to another (and their lipids may even be normal) but have considerably more particles and, thus, be at greater cardiovascular risk.

The ratio between ApoB and another important type of Apo called ApoA-1 (the major protein in HDL that is the “good” cholesterol) is also a useful measure of CVD risk. The ApoB/ApoA-1 ratio represents the balance between the “bad” and the “good” cholesterols. A lower ApoB/ApoA-1 ratio means that there is less unhealthy LDL relative to healthy HDL, suggesting a lower risk of CVD.

Can I get the Apolipoprotein B Test online?

Yes. You can get the Apolipoprotein B test from The Online Clinic.

Why is an Apolipoprotein B test important?

Key roles of Apo’s include stabilising lipoproteins and making lipids soluble in blood so they can be transported around the body. They also regulate enzymes involved in metabolising (breaking down and building up of) lipoproteins for energy and growth, regulate processes enabling cell receptors to identify and bind to lipoproteins in the blood, and help with the absorption of lipids into cells.

ApoB is responsible for cholesterol deposition in the walls of arteries, resulting in atherosclerosis – a progressive disease in which cholesterol and other lipids build up in arterial walls forming plaque. This process causes the arteries to harden and narrow and blood flow to be restricted. It can lead to serious heart and blood vessel complications, such as heart attack and stroke.

The clinical importance of measuring ApoB is that rather than how much cholesterol is in the blood, ApoB represents the number of lipoprotein particles (including LDL, VLDL, IDL, Lipoprotein(a)) that can get trapped in arterial walls and form plaques. Many small particles would increase the risk of them becoming lodged in the arterial walls. One person may have a similar LDL-cholesterol to another (and their lipid levels may even be normal) but have considerably more particles and, thus, be at greater cardiovascular risk.

Who should have their Apolipoprotein B level tested?

The ApoB test is generally used to build on the results obtained from the initial standard lipid tests.

The ApoB test can be used:

• In high-risk patients living with diabetes, high blood pressure, metabolic syndrome, and/or obesity
• In patients with high cholesterol or high triglyceride levels
• In patients with familial hypercholesterolaemia (high cholesterol levels) or hyperlipidaemia (high lipid levels), and/or with a family history of CVD
• In patients whose LDL-cholesterol is low or normal despite having other high-risk factors
• Where a more accurate and complete overview of cardiovascular risk is warranted
• To monitor lifestyle modifications or medications intended to increase HDL-cholesterol
• In the identification of gene mutations and variants that lead to higher ApoB levels.

How to test for Apolipoprotein B?

A few drops of blood are required for the ApoB test. Blood drops can be collected by a healthcare professional from a vein in your arm, or you can easily collect the sample yourself at home.

When collecting the blood sample yourself, a self-collection blood sample pack is provided by The Online Clinic, along with details of where to send the sample for laboratory analysis. You must carefully read and follow the instructions in the pack on how to collect a sample of your blood from a little finger. To summarise, a lancet is used to pierce the skin and the resulting blood droplets are collected into a collection tube up to the marked upper line (600 mcl). The blood collection tube is then sealed, gently inverted 5–10 times, labelled with your details, and mailed to the laboratory. Your healthcare professional will receive your test results and advise you on the findings.

What are normal Apolipoprotein B test results?

It is usual for normal ApoB ranges to vary between laboratories analysing the blood sample. ApoB reference values for males and females for:

• Children aged 1–6 years are less than 0.94 g/L.
• Children and adolescents aged 6–19 years are less than 0.85 g/L.
• Adults aged 19 years and older range 0.4–1.20 g/L.

Your target ApoB concentration may differ depending on what your healthcare professional considers best for you.

How long do results take for the Apolipoprotein B test?

Results are available within 3 days of the sample arriving at the laboratory. You will receive a PDF of your lab report with an interpretation from a doctor.

How to maintain normal Apolipoprotein B levels

To maintain normal and, particularly, to decrease ApoB, it is essential to follow a healthy lifestyle. This may be achieved with a Mediterranean-style diet that focuses on eating whole foods, vegetables and unsaturated fats (e.g., olive oil, oily fish and nuts), and increasing soluble fibre (e.g., oats, soya and beans), and foods containing plant stanols (e.g., nuts, legumes and cholesterol-lowering food products). It is important to reduce your consumption of saturated fats (e.g., red meat, cheese, butter), processed/ultra processed foods, refined carbohydrates, and sugar. The diet along with regular physical activity involving aerobic exercise for 2.5 hours/week will help you to maintain a healthy body weight. Factors that may worsen ApoB levels include more than 14 units of alcohol/week, smoking, poor/lack of sleep, and chronic stress.

For many people, a healthy lifestyle is insufficient to lower ApoB and treatment is also required. Medicines known as statins, ezetimibe, and PCSK9 inhibitors, as well as plant sterols/stanols can improve the ApoB to ApoA-1 ratio.

References

Brittanica AI (Thompson TE, Editors) 13 Jan 2026. In Lipid: Functions, origins, and recycling of apolipoproteins. Available from: https://www.britannica.com/science/lipid/Functions-origins-and-recycling-of-apolipoproteins#ref914032

Gloucestershire Hospitals NHS Foundation Trust. 31 Jul 2019. Apolipoproteins (Apo-A1 and Apo B). Available from: https://www.gloshospitals.nhs.uk/our-services/services-we-offer/pathology/tests-and-investigations/apolipoproteins-apo-a1-and-apo-b/

Ma Z, Zhong J, Tu W, et al. The functions of apolipoproteins and lipoproteins in health and disease. Mol Biomed 2024;5:53. doi: 10.1186/s43556-024-00218-7

Mendis S. Apolipoproteins. 21 Oct 2024. Available from: https://patient.info/doctor/investigations/apolipoproteins

Yun YM. Apolipoprotein B, Non-HDL Cholesterol, and LDL Cholesterol as Markers for Atherosclerotic Cardiovascular Disease Risk Assessment. Ann Lab Med. 2023;43(3):221-222. doi: 10.3343/alm.2023.43.3.221