Manhattan Cardiology’s cardiologist, Robert Segal, MD, speaks to Today.com about Normal blood pressure and how to read it and when to see a doctor

How common is it for people to have high blood pressure? How valuable can it be for patients to know their blood pressure?

It is far more common than I (health-professionals) wish it were. According to the American Heart Association, 77.9 million Americans have high blood pressure. That is about 1 out of every 3 adults.

Segal is quoted saying, “It is extremely valuable for patients to know their blood pressure, as it is one of many important indicators of health.” Firstly, high blood pressure usually has no symptoms, so you need to get tested in order to find out your blood pressure. For instance, according to the Mayo Clinic, very high blood pressure (180 over 120, say) can damage blood vessels, which is a preliminary stroke symptom. Likewise, according to the CDC, having high-blood pressure can also contribute towards developing heart disease. Segal is quoted saying, “In 2017, nearly half a million deaths in the U.S. included high blood pressure as a primary or contributing cause, so knowing your blood pressure is a matter of life or death. On the flip side, low-blood pressure comes with its own risks. The symptoms include fainting, dizziness, blurry vision and fatigue, all of which can be life-intruding and dangerous. Furthermore, its causes could be very serious: such as, low heart-rate, parathyroid disease, low blood sugar, diabetes, dehydration, blood loss and a B12/folate deficiency. All of these conditions are serious, which is why it is important to monitor your blood pressure, so as to work towards bringing it back to a normal range.

What do the blood pressure numbers mean? What is systolic pressure? What is diastolic pressure? Which number is most important?

There are two blood-pressure numbers. The top number is called systolic pressure and the bottom number is called diastolic pressure. Segal is quoted saying, “ Systolic pressure is the number that measures the amount of pressure your heart generates when pumping blood through your arteries to the rest of your body.” Diastolic pressure is the number that measures the amount of pressure in your arteries when your heart is at rest between beats. So the top number can be said to be measure blood pressure when the heart pumps and the bottom number can be said to measure blood pressure when the heart is not pumping. According to Harvard University, while both numbers are important and should be taken into great consideration, the top number (systolic) is more important and is focused on more by doctors. Greater risk of stroke and heart disease is more readily unveiled by analyzing systolic pressure rather than diastolic pressure.

What is normal blood pressure and how does this break down by gender and age? What are healthy and unhealthy ranges?

According to the American Heart Association, normal blood pressure is less than 120 systolic mm Hg (top number) and less than 80 diastolic mm Hg (bottom number). This breaks down by gender and age as follows: when we are younger, relative to when we are older, we can get away with slightly elevated blood pressure levels. For instance, a 20-year-old with a 130/81mmHg blood pressure will be far less at risk for a stroke than a 65-year-old with the same numbers. Hence, as we age we become more sensitive to elevations in blood pressure. And not just that, but our systolic blood pressure inherently increases with age, so we have to be more diligent with our lifestyle choices as we age, because our health can slip a lot more easily than it did when we were young. Finally, it is the case that on average, females have lower blood pressure than males –potentially due to the higher amount of androgen secretion (e.g. testosterone, which increases blood pressure) in males, and the protective aspects of estrogen from blood-pressure increases, which is evidenced by increases in blood-pressure after menopause.

For most people, a healthy range for blood pressure is generally from 120/80 mm Hg to 91/61 mm Hg. Anything above or below these ranges are considered either elevated or low, and in turn, should be addressed accordingly.

What about chronic diseases – how can these affect blood pressure?

To start with low blood pressure, here are a few diseases that can literally cause low blood pressure: malnutrition, septicemia, anaphylaxis, bradycardia (low heart rate), heart attack, heart failure, parathyroid disease, Addison’s disease, diabetes, and hypoglycemia (low blood sugar). High blood pressure, on the other hand, can be caused by the following diseases: kidney disease, diabetes, sleep apnoea, glomerulonephritis, thyroid problems, lupus, obesity, and scleroderma.

When can it fluctuate? What amount of fluctuation is OK?

Your blood pressure will fluctuate on a daily basis: stress, sex, exercise, laughter, eating, excitement, taking medicine, suffering from an illness, doing drugs and/or –but not only, as this list is long—sleeping, for instance, will cause your blood pressure to fluctuate. Fluctuation is the best when it is tied towards making your blood pressure normal most of the time. For instance, while exercise acutely increases blood pressure, it will contribute towards it’s chronically being in a normal range. Same with sleep: it acutely makes your blood pressure lower than normal, only to make it chronically normal. Hence, so far as fluctuations contribute to chronic normal blood pressure levels, then fluctuations are okay. When they do not, however, –for instance, when you have a disease, drug-habit, bad sleeping habit, and a high-stress life—but instead, contribute towards chronically elevating or depressing your blood-pressure levels, then fluctuations become not okay.

How can you get the best readings when taking blood pressure at home?

Segal is quoted saying, “A few things to consider: making sure the cuff size of the at home monitor fits you perfectly; asking your doctor to check the accuracy of your home device; take your blood pressure in the morning right before eating and last thing in the evening about 30 minutes after dinner, as, your are least stressed out during these times and there are no substances that will interfere with the readings; do not take any medications before taking your blood pressure; be as calm as you can prior to your readings.”

When is it important to see a doctor? When are patients at risk?

One thing is for certain: when your home tests are readily above or below normal ranges, you should see your doctor. Likewise, when you are experiencing symptoms of fatigue, nausea, dizziness, faintness, and drowsiness, that is another time you should see your doctor, as these are symptoms of blood pressure issues. Generally speaking, once you have a blood-pressure that has been elevated to 120-129 systolic and less than 80 diastolic mm Hg, you are more likely to develop high blood pressure unless you change your lifestyle for the better to get your blood pressure back into normal ranges. Once you are at 130-139 systolic or 80-89 diastolic, however, you have hypertension stage one, and lifestyle changes become more pertinent, as your risk for stroke or heart attack is much higher.

What is prehypertension? What can patients do to minimize risk of becoming hypertensive?

In terms of numbers, prehypertension is anything from 120-139 systolic or 80-89 diastolic mm Hg blood pressure. Segal is quoted saying, “Prehypertension is not an illness like hypertension; rather, it is a warning that illness is looming. This is due to the fact that those with prehypertension are twice as likely to develop high blood pressure than those with normal blood pressure levels.” For prehypertensive individuals, lifestyle changes are required to ensure not becoming hypertensive, not medication. Some recommendations include eating a diet that is mostly composed of nutritious, whole, mostly unprocessed foods, getting at least 30 minutes of moderate exercise per day (this could be as simple as walking), ensuring you are maintaining a healthy/lean body composition (10-15% body fat for men and 20-25% body fat for women) by controlling your weight, moderating your alcohol consumption, getting 7-9 high quality hours of sleep most nights, cutting out recreational drug-use and controlling your stress levels (ensuring they are low).


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