What Is Blood Pressure?

Pressure in Arteries Used to Assess Cardiovascular Health

Blood pressure is the pressure of circulating blood on the walls of arteries. It is an essential measurement for heart health since it is closely related to the force and rate of the heartbeat and the diameter and elasticity of the arterial walls. Doctors use blood pressure readings to help evaluate cardiovascular health.

Blood pressure is divided into systolic pressure (the top number) and diastolic pressure (the bottom number). The normal range for blood pressure for adults is less than 120 over 80 (120/80) millimeters of mercury (mm Hg).

What Is Blood Pressure?

Blood pressure is the pressure of circulating blood on the walls of arteries. It is closely related to the force and rate of the heartbeat and the diameter and elasticity of the arterial walls.

Types of Blood Pressure

There are two types of blood pressure. Systolic blood pressure is the amount of pressure exerting against your artery wall when the heart beats (the top number). Diastolic blood pressure measures the lowest blood pressure in the arteries (the bottom number).

Blood pressure readings for adults fall into five categories:

Blood Pressure Stages
Blood Pressure Status Systolic Diastolic
Normal 120 80
Elevated 130-139 or  80-89
Hypertension Stage 1 140 or higher and/or 90 or higher
Hypertension Stage 2 140 or higher or 90 or higher
Hypertension Crisis 180 or higher and/or Higher than 120

High or Low Blood Pressure

Hypertension is when your blood pressure is above normal. When blood pressure is too high for too long, it can significantly harm your health. Almost always, if you have hypertension, it is unlikely you will have any symptoms to make you aware.

Hypotension is when your blood pressure is too low or below normal. It can cause fainting, dizziness, and fatigue. Low blood pressure typically only presents a problem when linked to symptoms.

According to the American Heart Association, there is no specific number at which day-to-day blood pressure is considered too low.  Within certain limits, it is ideal to keep your blood pressure low. Low blood pressure only becomes problematic when it causes symptoms.

A blood pressure cuff at a doctor’s office.
A blood pressure cuff at a doctor’s office. Fuse/Getty Images

Symptoms of Abnormal Blood Pressure

High blood pressure develops most times without you knowing it. You can even have hypertension for years without any symptoms. When high blood pressure is undetected, it is dangerous because it can damage organs and arteries. This is why hypertension is called the “silent killer.”

Symptoms may appear, but only after blood pressure has reached a crisis stage. At this stage, you may experience severe chest pain, severe headache and blurred vision, nausea and vomiting, shortness of breath, and or seizures. Often you will only discover you have high blood pressure during a physical exam performed for another reason.

Unlike hypertension, symptoms are often present in people who experience hypotension. Symptoms of blood pressure that is too low include:

  • Fainting
  • Dizziness or lightheadedness
  • Dehydration and unusual thirst
  • Rapid, shallow breathing
  • Blurred vision
  • Cold, clammy, pale skin
  • Depression
  • Nausea
  • Fatigue
  • Lack of concentration

How Blood Pressure Is Evaluated

A healthcare professional will take your blood pressure with an inflatable arm cuff around your arm and a pressure-measuring gauge. It is important to have a proper fitting arm cuff to get a correct reading. Ideally, your blood pressure should be measured in both arms.

Doctors confirm hypertension over a series of separate appointments. They will take two to three readings at each visit before making a hypertension diagnosis. They will do this for two reasons—people can have varying blood pressure readings throughout the day, and it can be unusually elevated at doctors’ visits because of anxiety (white coat hypertension).

Hypotension is diagnosed by blood pressure, medical history, and physical exam. Additionally, your doctor may:

  • Run blood tests: These can provide an overall picture of your health. Labs may show an abnormal result that may be linked with hypotension.
  • Perform an electrocardiogram (ECG) in the office: The ECG detects structural problems in your heart, irregularities in your heart rhythm, and problems with oxygen and blood supply to the heart muscle.
  • Order a tilt table test: If you experience low blood pressure, a tilt table test may determine how your body responds when changing position.

Causes and Risk Factors

There are numerous causes and risk factors for abnormal blood pressure.

Causes of hypertension include:

  • Age: Blood pressure increases with age.
  • Race: Blacks, in particular, are more prone to hypertension as well as conditions linked to it.
  • Family history: Hypertension runs in families.
  • Being overweight or obese
  • Poor diet
  • Smoking and use
  • Excessive alcohol
  • Sedentary lifestyle
  • Stress
  • Medication
  • Pregnancy

Causes of hypotension include:

  • Heart problems
  • Dehydration
  • Blood loss
  • Severe infection (sepsis)
  • Severe allergic reaction (anaphylaxis)
  • Endocrine problems
  • Malnutrition
  • Pregnancy
  • Certain medications

Treatment

Treatment for high blood pressure includes lifestyle changes, medications, or both.

A healthy, low-sodium diet, not smoking, exercise, and weight loss are ways to lower blood pressure on your own. Your doctor may also need to prescribe blood pressure-lowering medication.

Low blood pressure that doesn’t cause symptoms or causes only a few symptoms rarely requires treatment. Treatment depends on the cause of your hypotension. If there is no diagnosable cause, your doctor may recommend the following to raise your blood pressure:

  • Eat more salt: Sodium can raise blood pressure, which is helpful to people with hypotension. For older adults, too much salt can lead to heart failure, so it’s key to check with a doctor first before increasing salt intake.
  • Drink more fluids: Water increases blood volume and prevents dehydration. Both are important steps in treating hypotension.
  • Lifestyle changes: Wear compression stockings, avoid standing for a long time, and get up slowly when rising to stand.
  • Medications: Your doctor can prescribe drugs to increase blood volume or blood pressure.

Complications

Abnormal blood pressure makes you more at risk for other health conditions. This is why it is important to treat hypertension, in particular, early. Uncontrolled hypertension can even be fatal. It can cause:

  • Hardening and narrowing of the arteries, which makes the heart work harder
  • Damage to the heart, brain, eyes, and kidneys
  • Heart attack, heart failure, and stroke
  • Kidney disease
  • Dementia
  • Aneurysm

A Word From Verywell

It is important to know your blood pressure status throughout your life. But the good news is if your blood pressure becomes abnormal, there are lifestyle changes and medications available to keep it under control. If you have concerns or more questions about your blood pressure, contact your doctor.

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Article Sources
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