Your cholesterol levels can affect your risk of heart disease and stroke. And the longer you have high cholesterol, the higher your risk.

That’s why leading medical organizations recommend checking your cholesterol regularly and, in some cases, working to lower it even when it’s slightly elevated. Last month, the American College of Cardiology and other medical organizations released new guidelines to help patients and doctors know what cholesterol levels are most appropriate and what medications might be helpful.

We asked doctors to explain the recommendations in detail.

To start, know your levels.

The guidelines recommend that adults, ages 19 and older, have their cholesterol tested at least every five years. (Before that age, children should have their cholesterol tested once, between ages 9 and 11, to detect hereditary hypercholesterolemia.)

A lipid profile, which can be done through a blood draw at your primary doctor’s office, tests for various types of cholesterol. Of these, doctors focus primarily on low-density lipoprotein (LDL), a “bad” cholesterol that can build up on the walls of your arteries. “We have overwhelming evidence” that the lower your LDL levels, the lower your risk of having a cardiovascular event such as a heart attack or stroke, said Dr. Erin D. Michos, associate director of preventive cardiology at Johns Hopkins University School of Medicine.

The guidelines also recommend that all adults have their levels of lipoprotein(a), a genetically determined form of cholesterol, measured at least once. Lp(a) increases the risk of heart disease, independently of other lipid levels. “It amplifies any risk you already have,” said Dr. Ann Marie Navar, associate professor of cardiology at UT Southwestern Medical Center in Dallas. We reach our adult levels in childhood and remain relatively stable throughout life, with some exceptions.

There is another, less used test for a different lipoprotein called ApoB. According to Dr. Navar, this is perhaps the best measure of cholesterol-related risk, as it reflects the total number of “bad” cholesterol particles, including not only LDL, but also Lp(a) and another type called vLDL. This makes it a more reliable measure, especially for people with metabolic diseases, such as diabetes and cardiovascular-renal-metabolic syndrome, due to differences in the size and density of LDL particles in these patients.

Determine your individual risk.

It’s never too early to talk to your doctor about your risk for heart disease, and you should adopt heart-healthy habits, such as following a Mediterranean or DASH diet and exercising regularly, the sooner the better. But starting at age 30, the conversation can include a real prediction of your future risk. The guidelines use a new calculator, called PREVENT, that includes risk factors that were not previously taken into account, such as body mass index and kidney disease.

Evaluates both short-term risk (10 years) and long-term risk (30 years).

Measuring long-term risk is especially useful for people ages 30 to 59. Doctors might evaluate a younger patient who is not at risk for heart disease in the next 10 years, but is at risk in the long term, and recommend that he start taking a statin.

“We want to reduce your lifetime exposure” to these bad cholesterol particles, Dr. Michos said. “The risk lies not only in the height of the level, but in the number of years that the arteries are exposed to these high levels,” similar to how doctors consider “pack-years” of smoking.

People with a low 10-year risk generally do not need to start taking medications unless they have an LDL level of 160 mg/dL or higher, or a high 30-year risk.

For people at borderline or intermediate risk, coronary artery calcium (CAC) scoring, which uses a low-dose CT scan to detect plaque buildup in the arteries of the heart, may be helpful in decision-making. This evidence can be a powerful incentive for asymptomatic patients to take medications, said Dr. Martha Gulati, a professor of cardiology at the DeBakey Cardiovascular Center at Houston Methodist Hospital.

When considering treatment, doctors also take into account other factors that could increase the risk of heart disease, such as South Asian ancestry, diabetes, early menopause, preeclampsia, or gestational diabetes, for example. They also consider inflammatory conditions such as rheumatoid arthritis and psoriasis, since inflammation contributes to the buildup of plaque in the arteries.

Know your objective.

The new guidelines set specific target levels of LDL based on short- and long-term risk of heart disease.

•For general prevention of heart disease in people at borderline or intermediate 10-year risk who do not have diabetes or heart disease, the goal is an LDL level less than 100 mg/dL.

•For patients at high risk at 10 years, people with long-term type 2 diabetes or diabetes complications, or people with CAC scores greater than 100, the goal is less than 70 mg/dL.

For most patients who have already had a heart attack or stroke, the goal is to keep cholesterol below 55 mg/dL. This might seem like an overly ambitious goal. However, according to Dr. Michos, “with a very intensive reduction in cholesterol, we can reduce atherosclerotic plaque, thus reducing the risk of future cardiovascular problems.”

Work with your doctor to find the right medication plan.

Most patients with persistently high cholesterol levels will need medication. Statins, which prevent the liver from making cholesterol, remain the first-line treatment. “They are economical,” said Dr. Gulati. «We have had them for more than four decades. “They reduce adverse cardiovascular events.”

“They are good medications despite their bad reputation,” he added, referring to common concerns about side effects. He noted that in randomized controlled trials, people who took a placebo experienced the same side effects as those who took statins.

But there are also many other medications available to doctors, such as ezetimibe, which inhibits the absorption of cholesterol from food; bempedoic acid, which blocks cholesterol production in the liver; and a much newer class of drugs called PCSK9 inhibitors, which help the liver remove LDL from the blood. (PCSK9 inhibitors are currently approved as injections, but trials are also underway with a pill form.)

“If you try a statin and you don’t tolerate it, we have other medications,” Dr. Navar said. “If you try a statin but don’t reach your therapeutic goal, you may need more than one medication.”

“There are many options available,” he added.