In Depth Cholesterol Testing

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Previously published on Answers.com.

Those at high risk for cardiac disease – who have high cholesterol as well as other risk factors such as obesity, smoking, high blood pressure, and diabetes, among others – might consider additional, more in-depth cholesterol testing to truly gauge cardiac risk.  These are not ordinary tests – though they are blood tests – and most doctors will not likely have recommended these without prompting. However, if you have high cholesterol and high cardiac disease risk, you might want to understand these tests so you can ask your doctor if you are a good candidate for these more in depth cholesterol tests.

What is Non-HDL Cholesterol and How Is It Calculated?

While not technically an additional test, Non-HDL cholesterol is an important measure that your doctor will likely not bring up unless you ask about it.  It is a key measurement – and is sometimes used as an additional benchmark for those with triglyceride levels over 200 mg/dL. Indeed, the National Heart, Lung, and Blood Institute’s National Cholesterol Education Program recommends that the non-HDL-C be considered along with typical cholesterol measures as it has been shown to be a very good predictor for cardiac risk.

It’s easy to measure non-HDL-C and does not require a separate blood test. Non-HDL-C is simply total cholesterol minus HDL cholesterol.  The tricky part is figuring out goal – if the resulting non-HDL-C figure is good or indicates an issue.  This is certainly something you should discuss with your doctor – but 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.)

Read more about non-HDL-C and an example of how to calculate it at my blog post, Do You Know Your non-HDL Cholesterol?

What is ApoB and What Does It Mean?

ApoB stands for Apolipoprotein B and it will not appear on a standard cholesterol test – this measure is an entirely different test from a standard lipid panel.  The ApoB test – along with non-HDL-C – is sometimes recommended for those at higher risk for cardiac disease.  The reason ApoB is a useful measure is that it provides information on the number of LDL particles.  People with a higher ApoB value than their LDL cholesterol tend to have smaller LDL cholesterol particles – and since these smaller particles can move more easily in the blood, that translates to higher cardiac risk.  Those with large or “fluffy” LDL cholesterol are potentially at lower risk of heart disease. That said, the American Heart Association does not yet recommend ApoB testing as standard procedure, but you should ask your doctor if you are a good candidate for a simple ApoB blood test.

What is LDL Particle Number and What Does It Mean?

Low Density Particle Number, or LDL-P, is another measure that some in the medical community say is a more accurate predictor of heart disease than Total Cholesterol or even LDL cholesterol. The LDL-P measure provides information about the specific size of the LDL cholesterol: Pattern B or Type B LDL particles are small sized LDL cholesterol whereas Pattern A or Type A LDL particles are larger and less dense – aka fluffier. Those with a high LDL-P in pattern A are considered more at risk for heart disease, though there is research that says that large amounts of pattern A LDL cholesterol might also be a risk factor for heart disease.  A great deal depends on other cardiac risk factors; if you have multiple heart disease risk factors (obesity, smoking) along with high cholesterol and/or high triglycerides, you should ask your doctor if you are a candidate for LDL-P testing.

Conclusion

You can compare your cholesterol results to goal by looking at your report – if your doctor didn’t give you a copy ask for one – and also by talking to your doctor.  For those who are at LDL goal, it’s easy to calculate non-HDL cholesterol, which is especially important for diabetics and those with high triglycerides.

ApoB and LDL-P can be measured by blood tests, though there are other measurement tools as well. Johns Hopkins Health Alerts explains the currently available testing: “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.”

Diving into your cholesterol numbers and calculating non-HDL cholesterol is a good jumping off point for discussion with your doctor about managing cholesterol.  Knowing about the ApoB and LDL-P testing will enable you to ask your doctor if these tests are right for you.

Did You Know?

LDL Particle Number can be measured with a blood test; it can also be measured by MRI.  Though unlikely that an MRI would be ordered for most high cholesterol patients, the MRI measurement of LDL-P has been shown to be a strong predictor of coronary heart disease.

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