Reading a lipid panel: apoB before LDL-C

A standard lipid panel reports total cholesterol, HDL-C, LDL-C and triglycerides. It is possible for all four to look acceptable while the number that matters most is elevated. That number is apoB.

Why particle count beats cholesterol content

Every atherogenic lipoprotein particle carries exactly one apolipoprotein B molecule. Measuring apoB therefore counts particles. LDL-C, by contrast, measures the cholesterol carried inside them, and the amount of cholesterol per particle varies considerably between people — particularly in insulin resistance, where particles tend to be small and numerous.

The consequence is discordance. In roughly one in five adults, apoB and LDL-C fall in different risk categories. Where they disagree, apoB has been the better predictor of events in the large cohort and Mendelian randomisation datasets.

What we do with it

ApoB is on every extended panel we run. It costs a few francs more than the standard lipid profile and it is the single addition that most often changes a decision. Where apoB is elevated and LDL-C is not, we treat the apoB.

A caveat worth stating

ApoB is a better marker, not a perfect one. It does not capture lipoprotein(a) mass, which is why we measure that once and never again unless something changes. And no lipid marker replaces the rest of the history.