Making Sense of Your Blood Pressure Numbers

by Laurel Leicht Health Writer

Do you know what your blood pressure is? And do you know what it means? When the nurse wraps that cuff around your arm, just like she’s done routinely for ages, it might seem like a throwaway moment at the doctor’s office. But you should listen up when you’re told your readout. Even if you feel perfectly healthy, there’s a good chance those numbers are higher than they should be: A whopping 46 percent of Americans have high blood pressure (a.k.a. hypertension), according to the American Heart Association, and some don’t even know it.

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Paying attention to your blood pressure reading is key, says physician Mary Ann Bauman, M.D., a spokesperson for the American Heart Association in Oklahoma City, because the numbers could clue you into an underlying health condition. “You don’t necessarily have symptoms with elevated blood pressure,” she explains, but if you know your number is high, your doctor can do a little more digging to figure out what’s going on. Making sense of your reading isn’t always easy, especially with recent changes to the guidelines on blood pressure and hypertension, but these tips can help.

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Getting an Accurate Reading

First things first. To ensure a proper blood pressure reading, you should avoid alcohol, cigarettes, and caffeine for at least 30 minutes before the test. Refrain from talking for five minutes prior and keep feet flat on the floor. All these variables can influence your numbers, says Dr. Bauman. The actual mechanism is simple: A cuff around your upper arm expands and the pressure builds until it completely cuts off blood flow to the arm. Gradually the pressure lowers, allowing blood to flow again.

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Know Your Top Number

As the cuff loosens, your doctor or a nurse will listen for your pulse with a stethoscope. (If you’re using an automated device, a machine will record this information automatically.) The first number recorded is called your systolic blood pressure. It’s measured in millimeters of mercury—abbreviated mm Hg. Your systolic blood pressure indicates the pressure that your blood places on your arteries while your heart is contracting.

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What Your Bottom Number Means

The second number in your reading is called your diastolic blood pressure. This measures the pressure your blood places on your arteries while your heart is relaxed. High diastolic blood pressure may indicate breathing difficulties and suggests that your heart is having difficulty contracting and relaxing properly. If your blood pressure is consistently elevated and lifestyle changes haven’t helped lower it, your doctor might want you to try medication to help get your numbers back down to a healthy range, says Nieca Goldberg, M.D., a cardiologist at New York University Langone Health Center.

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What’s Normal, What’s Not?

Normal, healthy blood pressure is any reading below 120/80, according to the American Heart Association’s latest guidelines. Even small amounts over the recommended numbers matter: If your systolic is between 121 and 129, for instance, you have what’s considered elevated blood pressure, regardless of whether your diastolic is less than 80. Elevated blood pressure might seem like no biggie, because it’s not officially “high,” but falling into that range doubles your chance of heart disease, says Dr. Bauman.

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The Range Where Risk Rises

If your reading is above 130/80, you have what’s considered hypertension stage 1. (You might know this better by its former name: prehypertension). Why the new terminology? “We found that patients weren’t taking the diagnosis of prehypertension seriously,” says Dr. Bauman. “The change in the name was to get people to recognize the urgency of their situation.” Adopting a healthier diet and exercising regularly can help you get out of stage 1 and back to a normal reading, Hypertension stage 2 starts at 140/90, and may require medication in addition to lifestyle changes to treat.

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In the Danger Zone

If your blood pressure soars higher than 180/120, you’ve entered a hypertensive crisis—and it’s as serious as it sounds. It can cause stroke, heart attack, and loss of consciousness. “Get to a doctor immediately,” advises Dr. Bauman. Warning signs that your blood pressure has spiked to this level include a severe headache, shortness of breath, and nosebleed (with no notable cause). If your blood pressure is sustained at this level, it can lead to kidney disease, fluid buildup in your lungs, and decreased vision.

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Both Digits Matter for Health

Know this: You’re not in the clear if just one of your two numbers to fall within the normal range. Both systolic and diastolic numbers are important, notes Dr. Goldberg. In fact, recent research published in the New England Journal of Medicine shows that both blood pressure numbers are predictors of various health outcomes. The study looked at data from 1.3 million people and found that individually, elevation in either number can be an indication of cardiovascular disease, myocardial infarction (a.k.a. heart attack), and stroke.

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Recognize an Emergency

Getting a slightly higher-than-usual blood pressure reading once in a while (say, after watching Parasite) isn’t a big deal. However, if you’re taking your blood pressure at home or at a pharmacy and find it’s in the hypertensive crisis range, don’t wait to seek help. Some people experience a hypertensive crisis without the classic symptoms (they may not even have chest pain) and the mortality rate for people in this range is 3.7%, found research in the journal Frontiers in Cardiovascular Medicine. Don’t wait for a total disaster—head to the ER now.

Laurel Leicht
Meet Our Writer
Laurel Leicht

Laurel Leicht is a writer and editor in Brooklyn specializing in health, fitness, lifestyle, and travel. Her work has appeared in outlets including O the Oprah Magazine, Women’s Health, Marie Claire, and Well+Good.