Heart to Heart conversation: The Basics of Blood Pressure
First, bring the data and the blood pressure cuff with you when you go to see your doctor. The doctor can compare your readings using your cuff and monitor to their devices. Doctors offices may have an electronic type of blood pressure measurement device or they may use the time honored method of using a stethoscope. With the latter technique, the stethoscope is used to hear the sound of blood when the flood flows through the cuff as the cuff pressure is lowered (unlike the home cuffs which use a pressure wave to sense blood pressure). Reviewing your blood pressure technique and comparing values to those obtained by stethoscope can add confidence that the pressure is being measured correctly. The pressure is usually about the same in both arms unless there are blockages or problems with the blood vessels.
As noted, "normal" blood pressure is 120/80 on average. But some people - particularly healthy women - run lower blood pressures such as 90/50. Much below 90 for the top number (systolic) can lead to too low a pressure ("hypotension") and problems with blood flow to vital organs. So generally, I usually try to keep patient's systolic blood pressure above 90 to avoid lack of flow to the brain causing passing out or lightheadedness.
For most people, optimal blood pressure should be less than 120/80 mmHg. Although there have been varying definitions over the years, most people would define hypertension to be present at a pressure of greater than 130/85 consistently. Most strategies for treatment of high blood pressure emphasize lifestyle changes initially such as lower salt, weight loss etc. The threshold at which blood pressure should be treated with medication varies for each patient. Similarly, if drug treatment is needed, the choice of drug must be individualized to the patient.