Prehypertension, also known as borderline hypertension, is a medical condition in which a patient's blood pressure is higher than normal, but not high enough for them to be diagnosed with hypertension. Patients with this condition should make lifestyle changes, or in some cases take medication to lower their blood pressure, in order to prevent developing hypertension. They should have their blood pressure checked regularly to see if they have progressed to full-blown hypertension.
Making the diagnosis of prehypertension rests on measuring a patient's blood pressure. Most often this is done with a blood pressure cuff, also known as a sphygmomanometer. A health care professional can manually measure the blood pressure by inflating the blood pressure cuff and using a stethoscope, or alternatively, a machine can be used to measure the blood pressure. Two numbers are given: the systolic blood pressure — which is the pressure noted when the heart is actively pumping, and the diastolic blood pressure — which represents the resting pressure. Values are typically given in millimeters of mercury (mm Hg); desirable systolic pressures range from 90 to 119 mm Hg, and desirable diastolic values from 69 to 79 mm Hg.
Patients with systolic blood pressures ranging from 120 to 139 mm Hg, or diastolic blood pressures ranging from 80 to 89 mm Hg, are considered to have prehypertension. In order to validate this diagnosis, doctors or other health care professionals should measure the blood pressure on three different occasions. The most accurate readings are obtained when a patient is allowed to rest in a chair for at least ten minutes prior to having the reading taken. Patients should avoid drinking caffeine within three to four hours prior to taking the reading. Some patients have increased blood pressure simply from going to the doctor’s office, a condition known as white coat hypertension, and could benefit from having their blood pressures checked at home.
Treatment for prehypertension depends on the patient. Patients who are otherwise healthy should make lifestyle changes, such as stopping smoking, decreasing alcohol use, eating a low-salt diet, exercising more often, and eating more fruits and vegetables. Some patients with high-risk conditions including diabetes or coronary artery disease might need to take anti-hypertensive medications if their blood pressures are in the prehypertensive range.
Having prehypertension puts a person at risk for developing hypertension, or high blood pressure. Patients with hypertension are at increased risk for the development of heart disease, stroke, and kidney disease. Those who have been diagnosed with prehypertension should have their blood pressure checked yearly in order to monitor for improvements or elevations in blood pressure values.