Although high blood cholesterol is an established risk factor for heart disease and stroke, many people are not aware of the reason for this relationship. Cholesterol and triglycerides are fats transported in the blood inside carrier vehicles called lipoprotein particles. The greater the number of lipoprotein particles, the more these particles move into the wall of arteries throughout the body.
Following entry into the artery wall low density lipoprotein (LDL) particles directly promote development of atherosclerosis ("hardening of the arteries") and increase risk for heart attack and stroke. High density lipoprotein (HDL) particles work in several ways to decrease atherosclerosis and cardiovascular risk. As a result, increased numbers of LDL particles, as well as decreased numbers of HDL particles, are significant risk factors for future cardiovascular disease.
Because of difficulty in directly "counting" lipoprotein particles measurement of cholesterol carried by particles (i.e., LDL cholesterol and HDL cholesterol) has been used for many decades as a surrogate to estimate LDL and HDL levels.
This approach only works if lipoprotein particles contain a known amount of cholesterol per particle. For example, if every can of soda has 12 ounces of liquid per can, then you can determine the number of cans by knowing the number of ounces of liquid measured.
Unfortunately, the amount of cholesterol carried inside lipoprotein particles is so variable that two people with the same LDL cholesterol (LDL-C) may have more than 100 percent different number of LDL particles (LDL-P).
We can now directly measure LDL-P easily and cost effectively in clinical practice. As a result, many studies have evaluated the frequency and clinical consequences of disagreement between LDL-P and LDL-C in various populations.
Multiple studies show that LDL-C and LDL-P levels differ substantially in approximately half of all people in healthy populations. Among patients with diabetes, pre-diabetes, or metabolic syndrome high LDL-P is present in up to 75 percent of patients with low LDL-C (less than 100 mg/dL). Importantly, when LDL-C and LDL-P substantially differ, numerous studies demonstrate that only LDL-P (not LDL-C) is predictive of future heart attacks or strokes.
So, does your cholesterol level predict cardiovascular risk? The short answer is only when cholesterol and particle number measures agree. If LDL-C and LDL-P are similar, both are equally predictive of future heart attacks and stroke. When LDL-C and LDL-P differ, risk tracks with LDL-P regardless of LDL-C level.
Several expert organizations now recommend treating LDL-P to specific target levels to ensure that individual patients achieve an optimal response to diet and medical management.
By using this strategy our practice is able to provide patients piece of mind that the true driver of cholesterol related risk - Lipoprotein Particle Number - has been ideally managed.
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