Blood Pressure

BLOOD PRESSURE

What Is High Blood Pressure?

High blood pressure is a blood pressure reading of 140/90 mmHg or higher. Both numbers are important.

High blood pressure is called the silent killer because it usually has no symptoms. Some people may not find out they have it until they have trouble with their heart, brain, or kidneys. When high blood pressure is not found and treated, it can cause:

The heart to get larger, which may lead to heart failure.
Small bulges to form in blood vessels. Common locations are the main artery from the heart (aorta); arteries in the brain, legs, and intestines; and the artery leading to the spleen.
Blood vessels in the kidney to narrow, which may cause kidney failure.
Arteries throughout the body to "harden" faster, especially those in the heart, brain, kidneys, and legs. This can cause a heart attack, stroke, kidney failure, or amputation of part of the leg.
Blood vessels in the eyes to burst or bleed, which may cause vision changes and can result in blindness

What Is Blood Pressure?

Blood is carried from the heart to all parts of your body in vessels called arteries. Blood pressure is the force of the blood pushing against the walls of the arteries. Each time the heart beats (about 60–70 times a minute at rest), it pumps out blood into the arteries. Your blood pressure is at its highest when the heart beats, pumping the blood. This is called systolic (sis-TOL-ik) pressure. When the heart is at rest, between beats, your blood pressure falls. This is the diastolic (di-a-STOL-ik) pressure.

Blood pressure is always given as these two numbers, the systolic and diastolic pressures. Both are important. Usually they are written one above or before the other, such as 120/80 mmHg (measured in millimeters of mercury, a unit for measuring pressure). When the two measurements are written down, the systolic pressure is the first or top number, and the diastolic pressure is the second or bottom number (for example, 120/80). If your blood pressure is 120/80, you say that it is "120 over 80."

Blood pressure changes during the day. It is lowest as you sleep and rises when you get up. It also can rise when you are excited, nervous, or active.

Still, for most of your waking hours, your blood pressure stays pretty much the same when you are sitting or standing still. That level should be lower than 120/80 mmHg. When the level stays high, 140/90 mmHg or higher, you have high blood pressure. With high blood pressure, the heart works harder, your arteries take a beating, and your chances of a stroke, heart attack, and kidney problems are greater.

What Is Normal Blood Pressure?

A blood pressure reading below 120/80 mmHg is considered normal. In general, lower is better. However, very low blood pressure can sometimes be a cause for concern and should be checked out by a doctor.

Doctors classify blood pressures under 140/90 mmHg as either normal or prehypertension.

Normal blood pressure is lower than 120/80 mmHg.
Prehypertension is blood pressure between 120 and 139 for the top number, or between 80 and 89 for the bottom number. For example, blood pressure readings of 138/82, 128/89, or 130/86 are all in the prehypertension range. If your blood pressure is in the prehypertension range, it is more likely that you will end up with high blood pressure unless you take action to prevent it.

There are two levels of high blood pressure: stage 1 and stage 2 (see the chart below).

Categories for Blood Pressure Levels in Adults (in mmHg, millimeters of
mercury)^*

Category	Systolic (top number)	Diastolic (bottom number)
Normal	Less than 120	Less than 80
Prehypertension	120–139	80–89
High blood pressure
Stage 1	140–159	90–99
Stage 2	160 or higher	100 or higher

For adults 18 and older who are not on medicine for high blood pressure; are not having a short-term serious illness; and do not have other conditions, such as diabetes and kidney disease.

Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 mmHg would be stage 2 high blood pressure.

There is an exception to the above definition of high blood pressure. A blood pressure of 130/80 mmHg or higher is considered high blood pressure in people with diabetes and chronic kidney disease.

What Causes High Blood Pressure?

In many people with high blood pressure, a single specific cause is not known. This is called essential or primary high blood pressure. Research is ongoing to find the causes of essential high blood pressure.

In some people, high blood pressure is the result of another medical problem or medicine. When the cause is known, this is called secondary high blood pressure.

Who Is At Risk for High Blood Pressure?

Many people get high blood pressure as they get older. There are things you can do to help keep your blood pressure normal, such as eating a healthy diet, maintaining a healthy weight, and getting enough physical activity.

Your chances of developing high blood pressure are also higher if you:

Are overweight
Are a man over the age of 45
Are a woman over the age of 55
Have a family history of high blood pressure
Have prehypertension (that is, blood pressure in the 120–139/80–89 mmHg range)

Other things that can raise blood pressure include:

Eating too much salt
Drinking too much alcohol
Not getting enough potassium in your diet
Not doing enough physical activity
Taking certain medicines
Having long-lasting stress
Smoking (smoking can cause a temporary rise in blood pressure)

How Do You Know Whether You Have High Blood Pressure?

Only your doctor can tell you whether you have high blood pressure. Most doctors will check your blood pressure several times on different days before deciding that you have high blood pressure. A diagnosis of high blood pressure is given if repeated readings are 140/90 mmHg or higher, or 130/80 mmHg or higher if you have diabetes or chronic kidney disease.

Blood pressure readings are usually taken when you are sitting or lying down and relaxed. Below are things you can do before getting your blood pressure taken:

Do not drink coffee or smoke cigarettes 30 minutes before having your blood pressure taken.
Wear short sleeves.
Go to the bathroom before the reading. Having a full bladder can change your blood pressure reading.
Sit for 5 minutes before the test.

You should ask the doctor or nurse to tell you the blood pressure reading in numbers.

You also can check your blood pressure at home with a home blood pressure measurement device, or monitor. It is important that you understand how to use the monitor properly. Blood pressure monitors can be bought at discount chain stores and pharmacies. Below are additional things to do when taking your blood pressure at home:

Sit with your back supported and your feet flat on the floor.
Rest your arm on a table at the level of your heart.
Take two readings, at least 2 minutes apart, and average the results.

Some people's blood pressure is high only when they visit the doctor's office. This condition is called white coat hypertension. If your doctor suspects this, you may be asked to check and record your blood pressure at home with a home monitor. Another way to check blood pressure away from the doctor's office is by using an ambulatory blood pressure monitor. This device is worn for 24 hours and can take blood pressure every 30 minutes.

How Is High Blood Pressure Treated?

Usually, the goal is to keep your blood pressure below 140/90 mmHg (130/80 mmHg if you have diabetes or chronic kidney disease). Ask your doctor what your blood pressure goal should be.

Some people can prevent or control high blood pressure by changing to healthier habits, such as:

Cutting down on salt and sodium and eating healthy foods such as fruits, vegetables, and low-fat dairy products
Losing excess weight and staying at a healthy weight
Being physically active for example, walking 30 minutes every day
Quitting smoking
Limiting alcohol intake

Sometimes blood pressure stays too high even when a person makes these kinds of healthy changes. In that case, it is necessary to add medicine to help lower blood pressure. Medicines will control your blood pressure, but they cannot cure it. You will need to take blood pressure medicine for a long time.

Blood pressure medicines work in different ways to lower blood pressure. Often, two or more medicines work better than one. Some medicines lower blood pressure by removing extra fluid and salt from your body. Others affect blood pressure by slowing down the heartbeat or by relaxing and widening blood vessels.

It is important that you take your blood pressure medicine at the same time each day and not skip days.

Key Points

Normal blood pressure is less than 120/80 mmHg.
Uncontrolled high blood pressure is dangerous and can lead to stroke, heart failure, heart attack, kidney failure, and blindness.
You have prehypertension if your top (systolic) number is usually between 120 and 139, or your bottom (diastolic) number is usually between 80 and 89.
You have high blood pressure if your top (systolic) blood pressure number is usually 140 or higher, or your bottom (diastolic) number is usually 90 or higher. Both numbers are important.
If you have diabetes or chronic kidney disease, you have high blood pressure if your top number is usually 130 or higher, or your bottom number is usually 80 or higher.
Over half of all Americans aged 60 and over have high blood pressure.
African Americans are more likely to have high blood pressure than Caucasians.
High blood pressure is called the silent killer because it usually has no signs or symptoms.
Having your blood pressure checked is quick and easy.
You can control your high blood pressure through healthy lifestyle habits and taking medicines, if needed.
It is important to keep track of your blood pressure and keep it under control.
You can help prevent high blood pressure by choosing a healthy way of life.

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