*Geek Box: Apoliproprotein B
Known as ‘ApoB’, this marker has emerged as a refined measure of all atherogenic lipoproteins in circulation. Historically, LDL-cholesterol has been the focus of assessing cardiovascular risk, given this atherogenic lipoprotein has been established as causal in the process of atherosclerosis.
However, there are other lipoproteins with atherogenic potential; chylomicron remnants [‘remnants’ are smaller particles compared to their parent compound, are rich in triglycerides and cholesterol, and capable of penetrating the arterial wall], very-low density lipoprotein [VLDL] and VLDL remnants, and intermediate density lipoprotein [IDL]. All of these particles have the potential to penetrate the arteries, become trapped, and generate the processes of atherosclerosis.
This pool of atherogenic lipoproteins has not historically been measured with any accuracy; “non-HDL cholesterol” was a crude measure, taken by subtracting HDL out of the measure of total cholesterol. However, each atherogenic lipoprotein particle carries its fat and cholesterol in a protein wrapper called apolipoprotein-B [‘ApoB’]; consequently, measuring ApoB provides a direct measure of the exact number of atherogenic lipoproteins in circulation.
From 2019, the European Atherosclerosis Society have recommended a direct measure of ApoB to assess cardiovascular risk, where circumstances allow for it.