What’s your LDL-P and why should you care?

What's your LDL-P and why should you care? 

Richmond.com column

April 2008

For what a man would like to be true, that he more readily believes.
Francis Bacon

Last week the American College of Cardiology (ACC) and American Diabetes Association (ADA) issued a consensus statement saying that the measurement of LDL particle number (LDL-P) is a more accurate method of quantifying cardiovascular risk than traditional measurement of LDL cholesterol (LDL-C).

OK, so what? Well remember, this is a column on health and new discoveries and treatments to test; treat and prevent illness and disease. Both men and women's number one health challenge is heart attack and stroke and since the 50's medicine has been screaming about cholesterol so any new test or strategy to better manage this risk IS big news. The funny thing is this test has been around since 1999. Medicine is slow to change, so it may be up to you to ask your doctor is this test is right for you.

Now for some basic science, keep reading, don't be afraid. Cholesterol is a naturally occurring substance in all our bodies and important for many things like making hormones, cell membranes and insulating the nerves in your brain. Cholesterol is carried in particles within our blood called lipoproteins. There are several types of lipoproteins including High Density lipoproteins (HDL), Low Density lipoproteins (LDL), Intermediate Density lipoproteins (IDL) and Very Low Density lipoproteins (VLDL). Within these various subclasses, there are still more distinctions which relate to particle size and function.

An American doctor, Ancel Keys, in 1953 using data from his 'Seven Countries Study', concluded that diets high in fat resulted in more heart disease. Thus, the start to find “the” substance that caused this increase in disease. Early science identified elevated levels of total cholesterol as being highly correlated to heart disease and stroke. Much of our current practice of cholesterol management has come from information derived from the Framingham Heart Study, which started in 1948 and goes on today. During these early times, laboratory technology limits allowed only the measurement of total cholesterol and later discoveries allowed the refinement into the above mentioned subclasses.

We now know that it is the number of particles that carry cholesterol in the bloodstream, not the total amount of cholesterol that causes vascular disease. As the concentration of particles goes up inside the bloodstream, the more likely these particles are to enter the wall of the vessel resulting in the deposition of cholesterol inside the vessel wall, the earliest form of vascular disease. LDL-P is the measurement of these cholesterol transport particles.

Since 1999 LipoScience in Raleigh, NC, has been measuring the number of lipoprotein particles which carry cholesterol in our blood. This technology has resulted in large scale testing of LDL-P and has been used to retest the serum of patients in the Framingham Heart Study. This data shows people from the Framingham study who are in the lowest quartile of LDL cholesterol (LDL-C) measurement still had 37%  MORE cardiovascular events than those in the lowest quartile of LDL particle (LDL-P) measurement. In other words, you can have low cholesterol and still be at risk for vascular disease. This data is supported by another large trial more recently called the Multi-Ethnic Study of Atherosclerosis (MESA) trial.

Again, so what? Well here's the thing. There is something called discordance. Discordance is when your cholesterol measured by old fashion means, differs from your lipoprotein particle number. It is the number of lipoproteins which carry your cholesterol that is the BEST estimate of your cardiovascular risk, that thing that kills most of us, not your cholesterol level. If you cholesterol level looks low and you have discordance between your cholesterol level and your lipoprotein particle number, you can still be at a much greater risk; 37% greater in the Framingham study and that was in the people with the LOWEST LDL cholesterol!

I had the opportunity to recently visit the LipoScience headquarters and listen to Dr. William Cromwell their former Chief Medical Officer. Dr. Cromwell has spent the last 20 years researching the relationships of lipoprotein particles and vascular disease. LipoScience uses nuclear magnetic resonance to count the number of lipoprotein particles in a blood sample. Their technology has been available since 1999 and last week's policy statement from the ACC/ADA is the loudest pronouncement yet to the medical community to use this test for routine screening and ongoing management of elevated lipoproteins.

So, what your LDL-P?  I hope you have found this topic of interest, you should. Heart disease and stroke are preventable with today's proven technology. LDL-P is just one of several recent advances that are available to better understand your health risks. Carotid artery ultrasound scanning, high resolution coronary CT scanning, other high tech vascular inflammatory markers are all available to you to better predict your vascular risk. Many of these tests are not covered by your health insurance. Our medical system is ranked 37th worldwide in preventative care. Health insurance companies exist to make money for their shareholders, not take care of your health. You should take care of your health!  

Putting all these tests together, explaining their meaning, planning a your wellness program, making healthcare convenient and delivering it in an efficient manner is what the Executive Health Evaluation program does for 10 of the 13 Fortune 1000 companies here in Richmond.

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