Your Blood Pressure Is High — But Why?

According to the Centers for Disease Control and Prevention (CDC), nearly one-half of US adults have high blood pressure, which raises the risk for stroke and heart disease. Many factors can affect your blood pressure and cause a high reading, but they don't mean you have hypertension.

"In the short term, factors like stress, exercise or eating a meal can cause a rise in blood pressure, but that is not the same as having the disease of hypertension," says Anupam Kotwal, MD, and endocrinologist and assistant professor of medicine at the University of Nebraska Medical Center in Omaha. "That's why we ask patients to check their blood pressure morning and night on at least 12 days before we diagnose hypertension."

​Read more:​ The Ultimate Guide to Healthy Blood Pressure — and Why It Matters

The American Heart Association (AHA) defines hypertension as when the pressure inside your arteries is higher than it should be. The top blood pressure number (systolic) measures the pressure when your heart beats; the lower number (diastolic) is the pressure between beats. "If the average of all your blood pressure readings is 130 over 80 or higher, you may be diagnosed with hypertension," Dr. Kotwal says.

"Exercise, stress and white coat syndrome are all common causes of a short-term increase in blood pressure," he adds.

White coat hypertension is when blood pressure readings by your doctor are high, but they drop down to normal once you leave the office, which could be simply a stress reaction — but it could also mean you are at risk for sustained hypertension. In such cases, according to the Mayo Clinic, your doctor may ask you to wear a blood pressure monitor for up to 24 hours to see what your average blood pressure is.

Certain factors can give you a short-term rise in blood pressure (or a false high) 30 minutes before a reading, according to Harvard Health Publishing. These include smoking, drinking caffeinated beverages or alcohol, and exercising.

The AHA adds that, in addition to avoiding these short-term factors that raise blood pressure, you should be sure you are taking blood pressure readings correctly. If you're monitoring your blood pressure at home, or before a reading by your doctor, follow these steps:

• Empty your bladder.
  
• Sit in a comfy chair, legs uncrossed, with both feet on the ground for at least five minutes before the reading is taken.
• Place cuff snuggly on bare skin, with your arm resting at chest height, preferably on a table.
  
• Measure your pressure at the same time each day.

Causes of long-term hypertension are called risk factors, and "there are two types of risk factors for developing hypertension," Dr. Kotwalsays. "Risk factors that you can control are called modifiable risk factors. Other risk factors, like your age and family history, are beyond your control. People who develop hypertension without any of the controllable risk factors may have a condition called essential or primary hypertension."

According to the AHA, risk factors you can't control, in addition to family history and aging, include race, ethnicity and gender and kidney disease.

Modifiable risk factors, according to the AHA, are:

• Lack of exercise
• A diet high in salt and saturated fats
• Having overweight or obesity
• Heavy alcohol consumption
• Sleep apnea
• High cholesterol
• Smoking
• High stress
  

Remember that hypertension usually has no signs or symptoms, which is why it has been called the "silent killer." You could be living with hypertension — as many people are — and not know it. Diagnosing hypertension and starting treatment could save you from a stroke or heart attack.

As the AHA notes, the only way to know you have high blood pressure is to have your blood pressure checked on a regular basis.

​Read more:​ The 10 Best Ways to Lower Your Blood Pressure Naturally