Special tests measure different types of fat particles in the blood. But whether the results can improve your health remains uncertain.
Earlier this year, a leading women's magazine featured an article about heart health in your 50s and beyond that included this advice: "During your annual physical, consider asking for a specialized vertical auto profile (VAP) test, a detailed lipid profile that helps identify plaque buildup in your arteries." (Lipid is another word for fat).
The VAP is one example of so-called advanced lipoprotein testing, which is a more detailed version of the usual cholesterol test, which doctors call a standard lipid panel or profile. The company that makes the VAP test claims that it improves doctors' ability to predict and treat heart disease. The test costs about the same as a standard lipid profile and is reimbursed by most insurance carriers. But for most people, there's little evidence that information from these tests would alter your doctor's advice.
Who might benefit from advanced cholesterol testing?
Some people could be helped by knowing more detailed information about the size, amount, and distribution of different lipoprotein particles in their blood. These include people who have:
"For the average person, the additional detail from advanced lipoprotein testing doesn't change what we would otherwise do in terms of treatment," says Dr. Jorge Plutzky, director of the Lipid/Prevention Clinic and co-director of Preventive Cardiology at Brigham and Women's Hospital and a faculty member at Harvard Medical School. "However, in a small percentage of people, we do turn to advanced lipoprotein testing and other nonstandard lipid tests to better define their risk," he says.
The many types of lipoproteins
Cholesterol, a waxy, yellowish fat found in cells throughout the body, travels through your bloodstream in tiny, protein-covered particles called lipoproteins. The lipid part of these particles contains both cholesterol and triglycerides, a type of fat used to store energy and deliver it to your muscles.
The smallest and densest particles are high-density lipoproteins (HDL), also known as "good" cholesterol. They remove cholesterol from artery walls and return it to the liver for excretion. Low-density lipoprotein (LDL) particles are known as "bad" cholesterol. They deliver cholesterol to cells in the artery wall, creating artery-clogging plaque that can trigger a heart attack or stroke.
A standard lipid panel measures levels of HDL, LDL, total cholesterol, and triglycerides in your blood. It may also include a measurement of very-low-density lipoprotein (VLDL)—particles made by the liver that carry a large amount of triglyceride.
LDL: Larger vs. smaller particles
Most clinicians focus on LDL because it's a good way to predict heart attack risk. But many people diagnosed with heart disease have LDL levels that aren't especially high. It turns out that LDL particles are not all created equal. Smaller, more tightly packed LDL has an easier time getting into arteries. Larger, fluffier particles may be less dangerous. Also, research suggests that a key protein on LDL called apolipoprotein B (apoB) is an important contributor for heart disease risk.
Advanced lipoprotein testing measures the size, distribution, and number of these subparticles as well as apoB. It may also include lipoprotein (a) and apolipoprotein A-1, the main protein on HDL.
A possible statin Rx
What if advanced lipoprotein testing reveals high levels of subparticles thought to potentially raise your risk of cardiovascular disease? "Your doctor may start you on a statin, or if you're already taking one, switch you to a higher dose, or a more intensive statin," says Dr. Plutzky. But so far, there are no data to support the health advantages of this practice.
And, as you can probably guess, the tried-and-true advice of eating a healthy diet, getting regular exercise, and maintaining a normal weight can lead to beneficial changes in abnormal lipoprotein values, including those that show up on advanced lipoprotein testing.
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