What are normal blood pressure ranges by age and gender?
Prehypertension typically occurs when the systolic pressure, or the first number, is between 120 and 139 and the bottom number, diastolic pressure, is between 80 and 89, claims the National Institute on Aging. This can lead to high blood pressure if not taken care of. High blood pressure occurs when the systolic pressure is over 140 and the diastolic pressure is over 90. There is also a condition called isolated systolic hypertension where the systolic pressure is high but the diastolic pressure is low. This situation is just as dangerous as high blood pressure.