Currently, we do not test LDL particle size (LDL-p). We measure ApoB because it is a better predictor of heart health risk and a more standardized measurement when compared to LDL particle size. ApoB can be measured through a serum test, whereas LDL particle size is measured primarily via NMR spectroscopy. This means LDL particle size testing is less comparable across labs, less standardized, and more expensive.
An LDL particle test gives the number of LDL particles and respective sizes of the particles in your bloodstream. An ApoB test is a measurement of the number of all potentially atherogenic particles, including LDL. So the LDL-p is actually already captured within the ApoB measurement but it's also capturing VLDL, IDL, chylomicron, and Lp(a) which are all potentially atherogenic particles.
Looking at apoB results alongside standard LDL results provides a solid picture of heart health. A concordant result (high LDL and high ApoB) means there is a high number of potentially atherogenic particles, which refers to high risk. A discordant result (high LDL and optimal ApoB) actually corresponds to lower risk because there are less potentially atherogenic particles.). If your results show optimal LDL and high ApoB, this demonstrates higher risk since it means a greater number of smaller and dense particles, which we know is more atherogenic.
We recognize the value of an LDL particle test, however, for InsideTracker users, an ApoB measurement alongside the other lipid panel markers is a more actionable metric of health and longevity.
Read this blog to learn more about ApoB and it’s relationship with LDL particle size and heart health: https://blog.insidetracker.com/impact-ldl-particle-size-apob-heart-health