For years, experts have urged Americans to keep their blood cholesterol levels healthy in order to minimize the risk of heart disease and stroke. For many people, that means getting a basic blood test for high cholesterol, also called a lipid panel. But there’s more you can do to find the underlying cause of high cholesterol.
A lipid panel measures your total cholesterol, as well as the components that make up that total number — your LDL cholesterol, which can put you at risk for heart disease; HDL cholesterol, which can protect against heart disease; and blood fats known as triglycerides, which can also raise your risk of heart disease and stroke.
If your lipid panel results are abnormal, your doctor may advise you to change your lifestyle by improving your diet, exercising more, and losing weight. If your LDL cholesterol is high, your doctor may also prescribe a cholesterol medication, such as a statin or other cholesterol-lowering drug.
Often, this basic cholesterol test is enough to guide treatment and reduce your risk for heart disease and stroke. But sometimes more information is needed to better understand what’s causing the high cholesterol, so your doctor will ask for more tests.
The additional information can help you and your doctor decide on the best treatment for you, according to Samia Mora, MD, associate professor of medicine at Harvard Medical School in Boston, and James Underberg, MD, president-elect of the National Lipid Association (NLA) and clinical assistant professor of medicine at NYU Langone Medical Center in New York City.
Your doctor may ask the lab for a look at your non-HDL cholesterol level, or request advanced lipid tests.
What Is Non-HDL Cholesterol?
Some experts say that calculating non-HDL cholesterol is a better way to determine heart disease risk than measuring LDL cholesterol alone.
“This is a simple calculation,” Dr. Underberg says, “but it adds a lot of additional information.” Simply subtract the HDL cholesterol from the total cholesterol to find the non-HDL number. “The non-HDL should be no more than 30 points higher than the LDL,” Underberg says.
An LDL cholesterol level of 100 milligrams per deciliter (mg/dL) or lower is considered healthy, so a non-HDL cholesterol total of 130 mg/dL or lower would be a healthy number to aim for.
What Are Advanced Lipid Tests?
Advanced lipid tests are simple blood tests that provide more information about your individual cholesterol characteristics and your health risks if you have high cholesterol, according to the NLA. The results of these tests can help your doctor identify what’s causing a cholesterol imbalance — and help determine the best treatment.
Cholesterol is carried along in blood as a part of lipoprotein particles. These particles have different sizes, densities, composition, and other factors, says Dr. Mora. Advanced lipid tests examine those specific characteristics that have been linked with health risks.
Insurance coverage for these advanced tests differs from plan to plan. If they’re not covered, the advanced lipid tests are typically about $50 each, though the costs may vary.
Of the advanced tests for high cholesterol that can be done from a single drawing of your blood, these are three of the most often–ordered:
- ApoB This test measures the concentration of lipoprotein particles that have a molecular marker called apolipoprotein B (ApoB) on their surface. This is the main protein found in LDL cholesterol, and measuring it can be a better indicator of heart disease risk than measuring LDL cholesterol in some people.
- LDL-P Also called LDL-particle number, this test measures the actual number of LDL particles that carry LDL cholesterol per liter of plasma, according to the NLA. Having a higher number of particles makes it easier for them to get into the walls of the arteries, which can set up a cascade of events that leads to the formation of artery-clogging plaque.
- Lipoprotein (a) This measures the level of a type of LDL cholesterol called lipoprotein (a), also called Lp(a). High levels can create unhealthy plaque buildup that leads to blocked blood vessels. According to researchers, elevated lipoprotein (a) can be an independent risk factor for heart disease.
How Tests May Help With Your High Cholesterol
To explain the ApoB and LDL-P tests (both of which look at the number of bad particles in your circulation) to his patients, Underberg often says, “If you want to know how bad traffic is, knowing the number of cars on the road — not the number of passengers in each one — is a better predictor.”
“When you measure LDL cholesterol [in the basic test] you are measuring the number of passengers,” he says. But what you really want to know is the number of cars — or how many of those particles are banging into your artery walls and putting you at risk for heart disease and stroke.
The advanced LDL particle test can also determine the size of the particles carrying cholesterol in your blood.
“Understanding particle size helps us understand what the issue may be,” says Underberg.
Someone with a high number of small, dense particles may have insulin resistance, for example. The body’s cells don’t use insulin properly to get blood sugar into the cells, and that elevates their risk of both heart disease and diabetes.
Taking a closer look at high cholesterol with these tests may change your treatment plan, Mora says. For instance, someone with high LDL cholesterol on the basic test may seem like a good candidate for statin treatment. But “you may not need a statin,” she says, if the tests for LDL-P and ApoB show a low number of cholesterol-carrying particles.
On the other hand, some people admitted to the hospital for heart attacks may have average or not very high LDL cholesterol, along with low HDL and high triglycerides, Mora says. But then if you check their ApoB, they have a higher particle number, which reflects their heart disease risk.
Those with the condition known as familial high cholesterol (hypercholesterolemia, or FH) often have elevated LDL cholesterol levels, elevated ApoB, and higher LDL particle numbers, Underberg says. “Particle size would most likely be large, but doesn’t have to be,” he says, for people who have FH.
A diagnosis of FH will mean a different path of treatment as compared with other types of high cholesterol, and also indicates that others in your family need to get screened for this inherited condition.