Bad Cholesterol, Worst Cholesterol

Oct. 27, 2003 -- If you think you know your cholesterol level, meet ApoB -- the newest, truest measure of heart health.

By now, everybody knows that the bad cholesterol is LDL. These low-density lipoproteins carry most of the cholesterol in your blood.

Apolipoproteins are tiny fat particles floating in the blood. Having a lot of one kind of Apo -- apolipoprotein B or ApoB -- means high risk of clogged arteries and heart attack.

Which Test?

So which is a better measure of your health: Your ApoB level or your LDL level? McGill University researcher Alan D. Sniderman, MD, and colleagues decided to find out. Their study appears in the Oct. 28 early access issue of Circulation: Journal of the American Heart Association.

The researchers looked at 1,522 people in the Insulin Resistance Atherosclerosis Study. These people underwent intensive examinations for heart disease, stroke, and diabetes risk factors. Sniderman and colleagues divided them into two groups. One was the group of patients who would be treated based on their LDL levels. The other was the group of patients who would be treated based on their ApoB levels.

The findings:

• 15% of people who would be treated based on LDL would not be treated based on ApoB.
• 25% of the people who would not be treated based on LDL, would be treated based on ApoB.
• Overall, about one in five people would have had a different treatment recommendation if the decision were based on ApoB instead of LDL.

Most worrisome were study participants with normal LDL but high ApoB. They were more likely to have abdominal obesity, high blood insulin levels, and high levels of clotting factors -- serious risk factors for diabetes and heart disease.

"These patients don't just have a cholesterol problem, they have an insulin-glucose metabolism problem," Sniderman says in a news release.

New Recommendation Coming Soon?

The LDL test is still valuable, Sniderman says. But the ApoB test adds valuable information. It's been used in Canada for two years. And while it's not yet recommended by U.S. authorities, these findings may mean it's time for a change.

"This is an important observation and needs to be considered carefully in light of prior data to determine whether current guidelines should be modified to recommend routinely monitoring ApoB levels in high-risk individuals," American Heart Association spokeswoman Alice Lichtenstein says in a news release.