You may have heard the term apoB in discussions about cholesterol, but what is it—and should you be paying attention to it? The short answer: yes. But whether you need to get it tested depends on your health situation.
What is apoB?
Apolipoprotein B (apoB) is a protein found on all the cholesterol-carrying particles that can cause plaque buildup in your arteries. This includes LDL (often called “bad” cholesterol), as well as VLDL, IDL, and lipoprotein(a). Each of these particles has one apoB protein attached, so measuring apoB tells you how many of these potentially harmful particles are in your blood.
How is apoB different from LDL cholesterol?
LDL cholesterol is a measure of the amount of cholesterol inside LDL particles. ApoB, however, counts the number of those particles. In most people—about 85–90%—these numbers match up pretty well. But in others, especially those with conditions like obesity, diabetes, or high triglycerides, LDL cholesterol might look normal while apoB is actually high.
That matters because the number of particles (apoB) is more closely linked to heart disease risk than the amount of cholesterol they carry.
Should you get tested for apoB?
Not everyone needs an apoB test. Right now, the guidelines suggest it mainly for people with certain risk factors like insulin resistance, high triglycerides, or ongoing risk for heart disease despite normal cholesterol. European guidelines are more proactive and recommend apoB testing more often for people at higher risk.
One reason apoB isn’t used more widely is that it’s less familiar to doctors and not covered by Medicare. But that’s likely to change, as recent studies show apoB is a better predictor of heart risk than LDL cholesterol.
Bottom line
If you have risk factors like diabetes, insulin resistance, high triglycerides, or unexplained heart risk, an apoB test could reveal hidden problems that a standard cholesterol test might miss. It’s a useful tool that can help to tailor a plan to better protect your heart.
