By John Messmer, MD

The general rule of thumb for blood pressure is: the lower is better. Even within the "normal" range, lower blood pressure reduces future risks.

Analyzing the  blood pressure "numbers"

Your doctor takes your blood pressure, tells you the results (a couple of cryptic numbers like "120 over 80"), and you nod. How important are they? Well, starting at 115/75, cardiac risk doubles for every 20/10 mm Hg increase in blood pressure. Normal blood pressure is 120 or below for systolic and 80 or less for diastolic for all adults. Generally, systolic pressures below 100 can be normal in small, thin people, but adult blood pressures typically exceed 100 systolic.

Systolics from 120 to 140 and diastolics from 81 to 89 are considered borderline or pre-hypertension when no other medical problems exist. When other conditions, such as, diabetes or kidney disease are present, systolics below 130 are preferred. Systolic pressures in excess of 140 or diastolics above 90 are considered hypertensive. A systolic greater than 160 or diastolic above 100 is considered severe. At these readings, damage takes years to develop in most cases, so physicians may not immediately start medication, preferring to try non-medical therapy first. However, when systolics exceed 200 or diastolics are more than 115, the risk of imminent damage, such as, a stroke or heart attack, is high and treatment is often begun immediately.

Blood pressure varies with activity and time of day

The more we exert ourselves, the more blood flow is needed to our bodies. Hard work or exercise requires more blood flow to the arms and legs, so blood pressure increases to accommodate the extra need. If it did not, any exertion would cause us to faint since the muscles would divert blood from our brains.

For evaluation purposes, resting blood pressure is the standard. Before measuring blood pressure, one should be seated quietly for at least five minutes. Speaking, eating, smoking and so on can cause the blood pressure to read higher than the resting pressure.

When is the best time to measure your blood pressure?

Readings can vary throughout the day so it's good to check at various times, but frequent repetitions in one sitting are not recommended. You should discuss the readings with your physician because what is acceptable and what requires treatment is complex and depends on many factors.

Everyone should have their blood pressure measured from time to time. Physicians will usually begin measuring it in children at about age 3. Although not as common as high blood pressure in adults, the incidence is increasing, probably due in part to increasing obesity in children. The normal range in children is lower than in adults and should be judged by the child's physician.

Get an annual blood pressure checkup

If there is a family history of high blood pressure in parents or siblings, annual blood pressure checks should begin in adolescence. Everyone, regardless of family history, should have their blood pressure checked periodically, certainly once a year. Diabetics should be checked several times a year because hypertension is devastating in diabetes. The blood pressure goal for diabetics is less than 130/80. Pregnant women are checked at each obstetric visit. Blood pressure goals are even lower for pregnancy since blood pressure drops in a normal pregnancy and any increase can compromise the circulation to the developing baby.

Conclusion: there are no symptoms for high blood pressure so check-ups are essential

People with healthy lifestyles can have high blood pressure, just as those who are sedentary, overweight and smokers can have normal blood pressure. Because there are no symptoms, it is essential that blood pressure be checked because the only way to find it is to look for it. Remember that you don't need to spend a lot of money (or even have health insurance) to get your blood pressure checked. Physician's offices aren't the only place you can get checked. Oftentimes, drug stores, health fairs, churches and other community organizations also provide this service.

For further information on potential causes of hypertension see the following article from TheDietChannel: What Causes Hypertension?

For further information on the treatment of hypertension see the following article from TheDietChannel: How is Hypertension Treated? and Lower Your Blood Pressure with the DASH Diet?