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July 13, 2012
Dear Mayo Clinic:
My mother is 62 and has had very low blood pressure for two years. She was hospitalized with blood pressure that dropped from 200/78 in bed to 60/40 sitting up. What could be causing this and what can be done to treat her?
Your mother has a condition called orthostatic hypotension. It happens when blood pressure falls significantly as a person stands up. Orthostatic hypotension can cause a variety of symptoms; the most common are feelings of dizziness and faintness.
Blood pressure is a measure of the pressure in a person's arteries during the active and resting phases of each heartbeat. When you stand, gravity causes your blood pressure to fall slightly as blood pools in your legs, lowering the amount of blood circulating back to your heart to pump. Normally, the drop in blood pressure is limited, though, because when you stand your nervous system triggers your blood vessels to narrow and your heart to beat faster. Sometimes, however, those nervous system responses do not happen the way they should, resulting in large swings in blood pressure from lying down to standing.
Blood pressure is considered normal in adults if it's approximately 120/80 millimeters of mercury (mm Hg). If the top number, known as systolic blood pressure, is 90 mm Hg or less, or the bottom number, diastolic blood pressure, is 60 mm Hg or less, that is generally considered low blood pressure. Symptoms caused by low blood pressure may include lightheadedness, fainting (also called syncope), blurred vision, tiredness, unsteadiness with walking, headache, confusion, or neck or back pain with walking.
Symptoms of orthostatic hypotension usually get worse in hot weather or when you are dehydrated. Some medications can also increase symptoms of orthostatic hypotension, including blood pressure medications, medications used to treat Parkinson's disease, antidepressants and bronchodilators, as well as caffeine, alcohol and appetite suppressants.
Treatment for orthostatic hypotension depends on the severity of symptoms. If symptoms are mild, no treatment is typically required. If they are moderate to severe, treatment can be helpful. Symptoms of low blood pressure are often triggered by dehydration, so drinking more water may help. Extra fluids increase blood volume and prevent dehydration. In some cases, adding salt to your diet can help, too. But your mother shouldn't do that without talking to her doctor first.
If extra water and salt don't decrease symptoms, medications are available that can help raise blood pressure, either by boosting blood volume or limiting the ability of blood vessels to dilate. In some cases, wearing compression stockings may also help reduce pooling of blood in the legs and increase blood pressure.
If an underlying medical condition is suspected as the source of orthostatic hypotension, tests to diagnose the disorder may be appropriate. Depending on the situation, looking for the cause of orthostatic hypotension can include tests of your heart, the glands in your body that make hormones (called endocrine glands), or your nervous system, among others. Ambulatory blood pressure monitoring — a test that involves wearing a blood pressure cuff for 24 hours that measures blood pressure automatically — may also be useful when evaluating orthostatic hypotension.
Your mother should talk with her doctor about how to best deal with orthostatic hypotension and explore possible causes. It is likely that with close monitoring and treatment, her condition can be effectively managed.
— John Graves, M.D., Nephrology/Hypertension, Mayo Clinic, Rochester, Minn.