Uncommon But Important Cholesterol Tests
Previously published on Answers.com.
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 can better predict your risk of heart disease?
These tests are not widely known and doctors do not often prescribe them. That said, these tests can be extremely helpful in understanding true heart disease risk. And thus determining if you truly should – or should not – take a statin medication.
Apolipoprotein B (ApoB)
Apolipoprotein B, or ApoB as it’s commonly referred to, is a simple blood test that measures the number and size of LDL (bad) cholesterol. Why this test is important is well explained in a Johns Hopkins Health Alert entitled ApoB – A Better Market For Heart Attack Risk than LDL Cholesterol? This article explains,
“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.”
Thus, 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.”
Low Density Particle Number (LDL-P)
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 the LDL Cholesterol (LDL or LDL-C) measurement commonly found on cholesterol test results is just the total amount of LDL cholesterol.
The two terms sound similar but are in fact quite different. As explained in The Difference Between LDL-C and LDL-P on the Docs Opinion 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. Dr. Sigurdsson explains in that online article, “…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.”
Dr. Sigurdsson goes on to explain that both LDL-P and ApoB are stronger predictors of heart disease risk than typical cholesterol measures. “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 (non-HDL-C)
While not another blood test, non-HDL Cholesterol is a third important measure to look at beyond the typical lipid panel test results. Non-HDL-C is simply your Total Cholesterol minus HDL Cholesterol. The only tricky part is figuring out your personal non-HDL-C goal. If your overall LDL cholesterol measurement 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 you cholesterol results report – they are also online or you can ask your doctor.) If your LDL cholesterol is not at goal, you should discuss this ratio with your doctor. For more info about non-HDL-C and how to calculate it see my blog post, Do You Know Your Non-HDL Cholesterol?
The simplest way to get tested is to ask your doctor. However some doctors are unfamiliar with these tests, or don’t believe they’re needed. If your doctor doesn’t want to order the tests, you can still get them – and you don’t have to travel to the Cleveland Clinic or the Mayo Clinic or Berkeley, California. The Johns Hopkins Health Report explains the various tests that measure LDL-P and/or ApoB: “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.” Ask your doctor and/or search for these tests in your local area.
For those with several risk factors for heart disease, statin medications are vital. But many who take statins might not need to be on these medications – their ApoB and LDL-P scores might indicate they have low heart disease risk even though their cholesterol levels are high. Conversely, many who are not on statins because their cholesterol levels are within goal might be at high risk for heart disease when that risk is assessed using ApoB and/or LDL-P testing. It’s likely these tests will become more common in the future, but for now, for a full picture of your personal risk of heart disease, ask your doctor about these tests and about your non-HDL-C ratio.
Getting the NMR LipoProfile test should be easy, even if your doctor won’t order it for you. On Mercola.com, Dr. Mercola states, “It’s easy to get and all major labs offer it, including LabCorp and Quest. Most insurance policies cover the test as well. Best of all, even if your doctor were to refuse to order it, you can order it yourself via third-party intermediaries like Direct Labs, or you can order the test online, and get blood drawn locally.”