Blood pressure: How low can you go?

Living Well

By Paula Havisto

Ministry Medical Group

Hypotension is the term used to describe low blood pressure, officially defined as a reading of 90/60 or below. And it ordinarily takes second place to hypertension or high blood pressure.

Keeping your blood pressure under the norm of 120/80 is important. High blood pressure is a major risk factor in strokes, heart attacks, kidney disease and other health problems. If you are able to keep your blood pressure well under that norm–even as low as 90/60–your clinician isn’t going to complain...as long as the drop is not sudden and does not cause other problems. After age 60, though, low blood pressure, known as hypotension, is common and can be a sign of an underlying problem that should be identified and treated.

Whereas hypertension is a silent disease, low blood pressure can cause rather disturbing symptoms such as lightheadedness, fainting, lack of concentration, blurred vision, nausea and fatigue. There are several reasons for these symptoms:

POSTURAL HYPOTENSION: The most common sudden drop in blood pressure is known as postural or orthostatic hypotension. Very common among seniors, it occurs when you stand up quickly from a seated or lying position.

Even when you’re young, standing up causes some blood to pool in your legs, which might cause your blood pressure to fall. But your body compensates by having your heart beat a little faster while your blood vessels contract to keep blood flowing to your brain. As you age, this mechanism does not operate as efficiently as it once did.

The result is a feeling of lightheadedness. And, if you don’t pay attention to the symptom and slow down, you’re likely to collapse to the floor.

Ironically, postural hypotension frequently occurs in persons who are taking diuretics, beta blockers or other medications to control their high blood pressure. If they fail to drink enough water, these medications may cause them to become dehydrated or have an electrolyte imbalance.

Extended bed rest, large varicose veins, thyroid problems, low blood sugar, severe heat and fatigue can also cause postural hypotension.

POSTPRANDIAL HYPOTENSION refers to a dip in blood pressure immediately after a meal. In this case, the demands of the digestive system divert blood flow that would normally go to the brain.

As with postural hypotension, this problem is more likely to occur in older persons, particularly those taking medications to control high blood pressure. Neurological disorders such as Parkinson’s disease may also be involved. And some individuals have a genetic predisposition.

To reduce the risk, you may want to consider eating smaller meals, lower in simple carbohydrates. Drinking 12 to 18 ounces of water 15 minutes before eating may help. Alcohol tends to dehydrate, so if you drink wine or beer with your meal, you should drink at least the same amount of water.

ATRIAL FIBRILLATION is an abnormal heart rhythm can cause many of the symptoms of low blood pressure–lightheadedness, dizzy spells, fainting, usually related to dips in blood pressure.

HEART FAILURE means a heart that has become weakened to the point that it is unable to pump blood efficiently. It’s a progressive condition, and eventually the pumping action of the heart deteriorates enough to keep blood from reaching the brain and other organs of the body. That leads to low blood pressure and poor blood flow to the brain, heart and other organs.

Other causes of hypotension include thyroid problems, a severe infection (septic shock), loss of blood and allergic reactions (anaphylaxis).

If you occasionally feel light headed or dizzy, you should mention it to your primary care clinician. You’ll likely learn that it’s only a normal part of aging. But it may also be a sign of a problem that needs attention.

Paula Havisto is a Certified Physician Assistant with Ministry Medical Group Family Medicine in Rhinelander.