Normal Blood Pressure Blood pressure is measured by taking two different measurements of the pressure within your arteries: systolic pressure and diastolic pressure. Systolic pressure, the first or top number of the blood pressure reading, is the highest level of pressure in your arteries, which occurs when your heart muscle contracts and forces a burst of blood into the aorta. Diastolic pressure, which is the bottom number, is the pressure that exists within your arteries between heart muscle contractions, which is when your heart is filling with blood. If your blood pressure reading is less than 120/80 millimeters of mercury or mm Hg (the unit of measurement that is used to describe blood pressure), you have normal blood pressure. This means that your systolic pressure is less than 120 mm/Hg and your diastolic reading is less than 80 mm/Hg. Blood pressure fluctuates throughout the day, so it is normal for your blood pressure to change from reading to reading. Your blood pressure is considered normal if it is less than 120/80 mm Hg most of the time. Prehypertension: When Blood Pressure Is Above Normal If your blood pressure is higher than 120/80 mm Hg — meaning that one or both of these numbers are higher — your doctor may take a number of readings over time, and possibly have you track your blood pressure at home to get more information before making a diagnosis of hypertension. If you have prehypertension, your blood pressure is above normal, but not high enough to warrant a diagnosis of hypertension. Prehypertension is considered to be a systolic pressure of 120 to 139 mm Hg or a diastolic pressure of 80 to 89. If your systolic pressure and diastolic pressure are not in the same category, you are considered to be in the more severe category of the two. People who have prehypertension are likely to eventually develop hypertension, unless they take steps to lower their blood pressure. If you have prehypertension, your doctor may recommend healthy lifestyle changes to prevent or delay the onset of hypertension. Stage 1 and Stage 2 Hypertension Hypertension is diagnosed when your systolic pressure is 140 mm Hg or above or when your diastolic pressure is 90 or above. In people who have diabetes or kidney disease, hypertension is diagnosed when blood pressure is 130/80 mm Hg or higher. The higher your blood pressure is, the greater your risk of developing blood pressure-related complications such as heart disease, heart failure, stroke, or kidney failure. The first stage of hypertension is called stage 1 hypertension. The systolic pressure is 140 to 159 mm Hg or your diastolic pressure is 90 to 99 mm Hg. The next stage of hypertension, stage 2 hypertension, is diagnosed when your systolic pressure is 160 mm Hg or higher or your diastolic pressure is 100 mm Hg or higher. A diagnosis of hypertension means that you need treatment to get your blood pressure under control. Your doctor may recommend lifestyle changes and high blood pressure medication to help manage your blood pressure. Hypertensive Crisis: A High Blood Pressure Emergency A systolic pressure reading above 180 mm Hg or a diastolic pressure reading above 110 mm Hg may mean that you are in hypertensive crisis and need emergency medical care. If you get a reading in this range at home, wait a few minutes and take your blood pressure again; call for emergency medical care if your blood pressure remains excessively high. Talk with your doctor about your blood pressure and what your numbers mean for you. Even if you have hypertension, taking steps to keep your blood pressure under control can reduce your risk of blood pressure-related health problems.
