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Diagnosing High Blood Pressure

NYU Langone preventive cardiologists are highly experienced in diagnosing and managing high blood pressure, also known as hypertension. Although this condition often has no symptoms, it can lead to heart conditions, including coronary artery disease and carotid artery disease. Hypertension also increases a person’s risk of stroke, and may over time cause damage to organs and systems throughout the body. 

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When there is too much pressure from blood flowing through the arteries, it can damage the walls of the arteries. Scar tissue develops, which can accelerate the development of plaque—a hard, waxy substance composed of fat, cholesterol, and calcium. When plaque builds up, it causes the arteries to narrow and forces the heart to work even harder to deliver blood and oxygen throughout the body. Plaques can also rupture, causing a heart attack or stroke.

More than one-third of people older than age 20 in the United States, or about 76 million adults, have high blood pressure.

A blood pressure reading includes two numbers and is measured in millimeters of mercury (mmHg). The upper number measures the pressure in your arteries when your heart beats, known as systolic pressure. The lower number measures the pressure in your arteries between beats, known as diastolic pressure.

Hypertension is defined as having a systolic reading of 140 mmHg or higher, a diastolic of 90 mmHg or higher, or both.

Risk Factors

There are two types of hypertension—primary and secondary. The primary form tends to develop gradually over many years, and may result from one or more risk factors. 

The secondary form of hypertension can occur as a result of underlying conditions, such as sleep apnea, type 2 diabetes, adrenal tumors, or hypothyroidism. It can also result from obesity or excessive use of alcohol or drugs.

Kidney disease and other kidney problems are closely associated with hypertension. The kidneys filter blood to remove waste. Hypertension can damage the arteries near the kidneys, affecting kidney function, which can further raise blood pressure. When kidneys are damaged or affected by an underlying condition, this can also raise blood pressure.

High blood pressure tends to run in families. If one of your parents has or had high blood pressure, you have a much higher chance of developing it. This risk is even higher if both of your parents have or had high blood pressure, and greater still if a sibling also has it.

Although people of any age can develop high blood pressure, age is a contributing risk factor. Nearly 67 percent of people age 60 or older in the United States have hypertension. Many people aren’t aware they have hypertension, so they aren’t taking steps to control it.

African Americans are more likely to develop hypertension than whites or Hispanic Americans, and tend to develop the condition at younger ages. Hispanic Americans and Latinos are more likely than whites to have undiagnosed or uncontrolled hypertension.

Certain lifestyle factors also increase the risk of hypertension. These include a diet high in salt, smoking, excessive alcohol consumption, and having a sedentary lifestyle. 

Diagnostic Tests 

If your doctor suspects that you have high blood pressure, he or she conducts a physical exam to determine your overall health and asks whether you have a family history of the condition, how often you exercise, and what your diet is like. Your doctor may then perform several diagnostic tests.

Blood Pressure Measurement

To measure your blood pressure, your doctor places an inflatable cuff around your arm, which measures the systolic pressure and the diastolic pressure. A normal blood pressure reading is 120/80 mmHg or lower. 

You are thought to have prehypertension—in which you are likely to develop high blood pressure if you don’t control it—if your blood pressure is between 120/80 mmHg and 139/89 mmHg.

High blood pressure is defined as 140/90 mmHg or higher. Severe hypertension is 160/100 mmHg and higher, and may require immediate or emergency treatment.

Your blood pressure changes throughout the day and night, depending on your stress and activity levels, health conditions, and even your body position. Your doctor may measure your blood pressure while you’re seated, lying on your back, and standing.

Depending on the degree of hypertension and other medical conditions, you may be diagnosed right away if your levels are consistently high. Your doctor may also suggest additional monitoring. 

If there are significant differences in blood pressure readings while you’re in different positions, this may help your doctor determine the cause as well as treatments.

Your doctor may prescribe a device you can use at home to check your blood pressure, or provide a 24-hour ambulatory blood pressure monitor that records readings several times an hour.

Heart Exam

Using a stethoscope, your doctor listens to the quality and intensity of the heart sounds, and the rate and regularity of the heart rhythm. Unusual sounds may be a sign of high blood pressure. 

Eye Exam

Damage to the retina, the light-sensitive tissue that lines the back of the eyes, can be a sign of hypertension, because chronic high blood pressure can increase pressure in the tiny blood vessels behind the eyes. 

Your doctor may conduct an eye exam with an ophthalmoscope, a lighted instrument used to look behind the eyes. Changes in the arterioles, small blood vessels in the retina, can offer valuable information about the severity and duration of hypertension.

Blood and Urine Tests

Your doctor conducts blood tests to look for evidence of underlying conditions that are related to high blood pressure. After blood is drawn, potassium, sodium, and cholesterol levels are analyzed, as well as glucose levels, which can determine if you have diabetes.

You may be asked to provide a sample of your urine, which can reveal kidney or liver problems.


Your NYU Langone doctor may recommend an echocardiogram. This ultrasound test uses sound waves to produce images of your heart. It enables your doctor to see how your heart is working as it fills with blood and pumps it to the rest of the body.

Your doctor uses the images from an echocardiogram to identify thickened heart muscles or enlarged cardiac chambers, which could be evidence of damage from high blood pressure.

Our Research and Education in High Blood Pressure

Learn more about our research and professional education opportunities.