Some things look one way on paper, and entirely different in real life. So it goes for cholesterol, one of the headliners on your annual bloodwork.

Despite all the fuss, you can actually have perfect numbers for HDL versus LDL cholesterol, and unhealthy arteries. Or you can also have lousy numbers, and healthy arteries.

We asked a heart expert to explain the truth about cholesterol — and where to get the answers you need.

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There’s no magic number for total cholesterol.

Several decades ago, researchers from the now-famous “Framingham study” collected data on thousands of patients, took several giant steps back, and saw a pattern between cholesterol levels and clogged-artery issues like heart attack and stroke. Understandably, we all began fixating on cholesterol, with the idea that as long as our numbers were good, our arteries would be too.

Unfortunately, that’s just not true. Since the Framingham study, other researchers have found that healthy patients with normal cholesterol levels can still have dangerous plaque buildup. And vice versa.

“A lot of people are under this impression of some magic threshold — that if your total cholesterol is below 200, that’s good. But total cholesterol can be misleading. There are far too many people that develop plaque disease and events in that range,” says Brett Nowlan, MD, a cardiologist with Hartford HealthCare’s Heart & Vascular Institute and Tallwood Men’s Health. “Likewise, some people devote their energy and concern to mildly elevated cholesterol levels, but have no plaque, and are actually at very low cardiac risk.”

The real question, if you’re paying attention, is whether or not you have plaque in your arteries.

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It’s not as simple as HDL versus LDL cholesterol, either.

We think of HDL cholesterol as “good cholesterol,” much loved for working against plaque. On bloodwork, the target is usually 40 or higher. LDL cholesterol is “bad cholesterol,” notorious for contributing to plaque. We’re usually told to keep it below 100.

Those HDL versus LDL cholesterol levels can be helpful guidelines, but they’re not exact. They’re based on averages across a huge group — which allows for big differences between one person and the next.

Plus, no amount of bloodwork can reveal what’s really going on inside your arteries.

For instance, if your HDL cholesterol isn’t working properly — which doesn’t show up in labs — you’ll have plaque even with stellar numbers. Or you may have the coveted four-to-one ratio of total cholesterol to HDL, but other damage to your arteries, like from smoking, diabetes or plain old genetics.

“If you have excellent cholesterol numbers but you have plaque in your arteries, it doesn’t matter what the numbers are,” says Dr. Nowlan. “You don’t treat according to a number. All cholesterol levels — be it total, LDL or HDL — are best evaluated in the context of whether there is plaque, or not.”

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If cholesterol tests aren’t the answer, what is?

A coronary artery calcium scan — also called a CAC scan or calcium scoring — is a type of very quick X-ray that shows if you have plaque buildup in your coronary arteries. Even without insurance, it’s affordable. And it’s worth it.

“If you have a heartbeat, you should have a calcium scan,” says Dr. Nowlan. “Think of it as part of your preventive care, like going to the dermatologist for a skin check or getting a routine colonoscopy or mammogram.”

If it reveals plaque in your arteries, then your doctor has the information they need to make a plan — including adjustments, if needed, to your cholesterol.

If it comes back clear, you can go about your life with a clean bill of health. Which is more than just great on paper.