Going Lo-Co

Cholesterol Tests Your Doctor Hasn’t Told You About

Posted on August 23, 2013

A standard cholesterol lipid panel  provides four measures: Total Cholesterol, LDL Cholesterol, HDL Cholesterol and Triglycerides.  But did you know that there are two other blood tests — and one ratio that’s easy to calculate — that can better predict your risk of heart disease?  Which means that even with high cholesterol, you might not need a statin medication if these tests show low cardiac disease risk.

Or you might think you don’t need a statin … and in fact do.

And yet, your doctor probably has not told you about these tests.  So let me.

Apolipoprotein B – or as it’s commonly referred to, ApoB, is a simple blood test that measures the number and size of LDL (bad) cholesterol. Why this test is useful is well explained by Johns Hopkins Health Alerts:

“The problem with using LDL cholesterol levels to determine heart attack risk is that the test measures only the amount of cholesterol in the LDL cholesterol particles, not the number or size of these particles. Apo B measurements, on the other hand, provide information on the number of LDL cholesterol particles.

For example, people with a higher apo B value than LDL cholesterol value tend to have smaller, denser LDL cholesterol particles. Studies have shown that small, dense LDL cholesterol particles are more strongly associated with heart attack risk than large, “fluffy” LDL cholesterol particles.”

So if you have high LDL cholesterol (goal is under 130), you might want to find out if you have the ‘fluffy’ kind of LDL (pattern A), or the more dangerous, small, dense type of LDL (pattern B). Indeed, the Johns Hopkins Health Alert goes on to explain, “Research published in The Lancet reviewed five studies of LDL cholesterol and ApoB in nearly 200,000 people. The researchers concluded that high levels of ApoB were more strongly linked with future heart attack risk than LDL cholesterol levels.”  Compelling, no?

Further, compelling information on the importance of ApoB and that studies suggest it might be lowered with carbohydrate restriction and excercies can be found in Apolipoprotein B (apoB) by Axel F. Sigurdsson MD, Ph.D., FACC on his Doc’s Opinion site, excerpted here:

“Several studies have shown that apoB may be a better predictor of cardiovascular disease risk than LDL-C. Furthermore, it has been shown that apoB may be elevated despite normal or low concentrations of LDL-C. ApoB also appears to predict on-treatment risk, when LDL-C has been lowered by statin therapy. The INTERHEART study found that the apoB/apoA1 ratio is more effective at predicting heart attack risk, than either the apoB or apoA1 measure alone.

Apo B containing lipoproteins are the ones that are most likely to enter the wall of the arteries. They are capable of trafficking cholesterol into the artery wall, and if present in increased numbers they may be the main initiating factor in atherosclerosis. Retention of ApoB containing lipoprotein particles within the arterial wall is an essential part of the process.”

Low Density Particle Number, or LDL-P, is a similar measure – and again, one that’s been shown to be a more accurate predictor of heart disease than the typical cholesterol measurements.  LDL-P measures the number of LDL particles in the blood, whereas LDL is just the total LDL cholesterol.

As explained in The Difference Between LDL-C and LDL-P on the DocsOpinion website, two people with the same LDL numbers can have vastly different heart disease risk because one has low LDL-P (fewer LDL particles of the type A, big, fluffy kind) while the other has high LDL-P, or a lot of LDL particles, of the small, dense, type B kind:

“…one person (person A) may have large cholesterol rich LDL particles, while another (person B) may have smaller cholesterol depleted particles. These two persons may have the same LDL-C concentration. However, person B will have higher LDL particle number (LDL-P). Despite similar levels of LDL-C, person B is at higher risk four future cardiovascular events. Furthermore, person B will have more small LDL-particles.”

The doctor who wrote this explanation of LDL-C vs. LDL-P goes on to explain that both LDL-P and ApoB are stronger predictors of heart disease risk than typical cholesterol measures:

“Some studies have suggested that the size of LDL-particles may be of importance. People whose LDL particles are predominantly small and dense, have a threefold greater risk of coronary heart disease.

ApoB and LDL-P both reflect the number of atherogenic lipoprotein particles. Measurements of ApoB and LDL-P are better predictors of cardiovascular disease risk than LDL-C. Furthermore, ApoB and LDL-P may predict residual risk among individuals who have had their LDL-C levels lowered by statin therapy.”

Non-HDL Cholesterol is a third important measure — and you don’t even need to take a blood test. Non-HDL-C is simply your Total Cholesterol minus HDL Cholesterol.  The tricky part is figuring out goal: if your LDL cholesterol is “at goal” you can roughly estimate your non-HDL-C goal by simply adding 30 to your LDL goal (these goals are usually on the cholesterol report – they are also online or you can ask your doctor.) And if it’s not at goal, discuss this ratio with your doctor.  I wrote about non-HDL-C and how to calculate it in this blog post, Do You Know Your Non-HDL Cholesterol?

While researching these in-depth cholesterol tests, I came across this compelling medical case study. It socked me in the gut, as this woman’s lipid panel cholesterol results were similar to mine, and yet it turns out from the additional LDL-P and ApoB testing that she was at high risk for cardiac disease. And needed statins.

Gulp.

So how do you get these tests?

I asked my internist about them months ago, and she said I didn’t need them — that my cholesterol numbers are fine. But now that I’ve read this case study I feel I would love more information.  I’ll have to ask her again about additional testing – especially now that I have more info.

And just so you know, you don’t have to travel to the Cleveland Clinic or the Mayo Clinic or Berkeley, California to get these tests. The Johns Hopkins Health Report explains,

“One widely used test, called the NMR LipoProfile, analyzes the size of lipoprotein particles in the blood by measuring their magnetic properties. Several others, including the LipoPrint and the Berkeley (from Berkeley HeartLab) use electrical fields to distinguish the size and other attributes of lipoprotein particles. Still another, known as the VAP (for Vertical Auto Profile) test, separates lipoprotein particles using a highspeed centrifuge.”

Even though my cholesterol is at goal, I’ve got to put in a call to my internist to ask about getting both the LDL-P and ApoB testing done. Will keep you posted.