Can your blood pressure be too low?                          

            Abnormally low blood pressure is known as hypotension and it can be dangerous. When blood pressure drops suddenly it might cause a fall that results in a head injury or a broken bone. If the decline in pressure is gradual and mild there may be dizziness, lightheadedness, blurred vision, nausea, a feeling of confusion or a rapid heartbeat. But how low can blood pressure go and not cause these symptoms? And is such asymptomatic low pressure dangerous?

            We use two numbers when measuring blood pressure. The first number (systolic) is always the higher one and it reflects the maximum pressure against the wall of an artery in the upper arm when the heart ejects blood. The lower number (diastolic) indicates the pressure in that artery just before the next heartbeat. The upper arm is selected because of sheer convenience.

            When the numbers exceed 140/90 the condition is known as hypertension but there is really no firm guideline for its opposite, hypotension. As a general rule, if a person’s blood pressure is below the generally accepted range of normal, ideally about 120/70, it doesn’t require treatment if there are no symptoms. Well-trained athletes, especially long-distance runners and walkers, often have a systolic blood pressure barely over 100. A child’s systolic pressure may be 90 or less.

            As we get older, blood pressure tends to rise. Although that is common it is not normal. The blood pressure of adult hunter-gatherers remains as low as it was in their youth. Americans’ pressures rise for three main reasons: overweight, lack of exercise and high sodium intake.  

            With some exceptions, new medical guidelines suggest no treatment in persons over the age of 60 if the systolic pressure is below 150 and the diastolic pressure is below 90. Although there is a risk of stroke at lower levels the side effects of prescription medications influenced those guidelines.

            Blood pressure monitors that are designed for home use are inexpensive, easy to use and reliable. Be aware that whether one’s pressure is measured at home or in a doctor’s office, a single reading might be misleading. In order to provide consistency and accuracy the patient should be relaxed and seated and the reading should be taken three times. Don’t be alarmed if the numbers seem low, perhaps 110/60, as long as there are no symptoms. You just might be one of those hunter-gatherer types.