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    36-37 β-lipoprotein
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    36-37 β-lipoprotein

    Beta-lipoproteins and apolipoprotein B: counting atherogenic particles, ESC/EAS apoB targets and older test methods.

    Beta-lipoproteins are the lipoproteins that migrate in the β-region on serum protein electrophoresis: LDL, together with VLDL remnants and IDL. All of them carry one molecule of apolipoprotein B (apoB) per particle. Measuring apoB is therefore the modern way to count atherogenic particles. Because every atherogenic particle carries exactly one apoB, apoB reflects their number more accurately than cholesterol does. This matters especially in people with diabetes, obesity, high triglycerides or kidney disease, whose LDL particles are small and cholesterol-poor.

    Lipid profileApolipoprotein BAtherogenic particles
    Moderate risk goalapoB < 100 mg/dL (1.0 g/L)
    High risk goalapoB < 80 mg/dL (0.8 g/L)
    Very high risk goalapoB < 65 mg/dL (0.65 g/L)
    One particle= one apoB molecule
    Lipoprotein classes from largest to smallest: chylomicrons, VLDL, IDL, LDL and HDL, with their size, main lipid cargo and role in atherosclerosis Blood lipoproteins (not to scale) Chylo-VLDLIDLLDLHDL 75–1200 nm30–80 nm25–35 nm18–25 nm5–12 nm dietary TGliver TGTG + cholesterolmostly cholesterolcholesterol, protein remnants atherogenicatherogenicatherogenicmain atherogenicreverse transport apoB-100 on VLDL, IDL, LDL apoA-I on HDL ← larger, lighter, more triglyceride smaller, denser, more protein →
    Figure 1. VLDL, IDL and LDL (the beta-lipoproteins) each carry one apolipoprotein B molecule, so apoB counts the atherogenic particles.

    Why count particles rather than cholesterol

    Two people can have the same LDL cholesterol but a very different number of LDL particles: many small particles carry less cholesterol each. The risk of atherosclerosis follows the number of particles entering the artery wall. When LDL-C and apoB disagree ("discordance"), risk tracks apoB more closely. The 2019 ESC/EAS guidelines recommend apoB as an alternative risk marker and secondary treatment target, particularly with high triglycerides, diabetes, obesity or very low LDL-C.

    Older "beta-lipoprotein" tests

    Some laboratories still report "beta-lipoproteins" measured by precipitation (turbidimetric) methods in their own units. These results are not directly comparable with standardised apoB assays. Use the reference range given by the laboratory, and prefer apoB, LDL-C or non-HDL-C for risk assessment.

    Causes of high apoB

    • Familial hypercholesterolaemia and familial combined hyperlipidaemia
    • Insulin resistance, type 2 diabetes, metabolic syndrome, abdominal obesity
    • Hypothyroidism, nephrotic syndrome, chronic kidney disease
    • Diet high in saturated fat and refined carbohydrates

    Very low apoB is found in rare inherited conditions (hypobetalipoproteinaemia, abetalipoproteinaemia), which may cause fat malabsorption and deficiency of fat-soluble vitamins.

    What to do

    A high apoB or beta-lipoprotein value should be discussed with a doctor together with LDL-C, triglycerides and overall cardiovascular risk. The same measures that lower LDL-C, such as diet, physical activity, weight control and, if indicated, statins, also lower apoB.

    References

    1. 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
    2. Ference BA, Ginsberg HN, Graham I, et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J. 2017;38(32):2459–2472. doi:10.1093/eurheartj/ehx144
    3. Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol. Circulation. 2019;139(25):e1082–e1143. doi:10.1161/CIR.0000000000000625

    This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.

    Published on 13 May 2024