Tests and diagnosis

By Mayo Clinic Staff

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The goal in evaluating orthostatic hypotension, as with all forms of low blood pressure, is to find the underlying cause. This helps determine the correct treatment and identify any heart, brain or nervous system problems that may be responsible for your low blood pressure. To help reach a diagnosis, your doctor may recommend one or more of the following:

  • Blood pressure monitoring. Your doctor will measure your blood pressure both while you're sitting and while you're standing and will compare the measurements. Your doctor will diagnose orthostatic hypotension if you have a 20 millimeters of mercury (mm Hg) drop in your systolic blood pressure or a 10 mm Hg drop in your diastolic blood pressure within three minutes of standing up, or if standing causes signs and symptoms.
  • Blood tests. These can provide a certain amount of information about your overall health as well as whether you have low blood sugar (hypoglycemia) or a low number of red blood cells (anemia), both of which can cause low blood pressure. Your doctor will also check to see if you have diabetes.
  • Electrocardiogram (ECG). This noninvasive test detects irregularities in your heart rhythm or heart structure, and problems with the supply of blood and oxygen to your heart muscle.
  • Echocardiogram. This noninvasive exam, which includes an ultrasound of your chest, shows detailed images of your heart's structure and function. Ultrasound waves are transmitted, and their echoes are recorded with a device called a transducer that's held outside your body. A computer uses the information from the transducer to create moving images on a video monitor.
  • Stress test. Some heart problems that can cause low blood pressure are easier to diagnose when your heart is working harder than when it's at rest. During a stress test, you'll exercise, such as walking on a treadmill. Or, you may be given medication to make your heart work harder if you're unable to exercise. When your heart is working harder, your heart will be monitored with electrocardiography or echocardiography. Your blood pressure also will be monitored.
  • Tilt table test. A tilt table test evaluates how your body reacts to changes in position. During the test, you lie on a table that begins flat and then tilts to raise the upper part of your body, which simulates the movement from a horizontal to standing position. Your blood pressure is taken frequently as the table is tilted.
  • Valsalva maneuver. This noninvasive test checks the functioning of your autonomic nervous system by analyzing your heart rate and blood pressure after several cycles of a type of deep breathing: You take a deep breath and then force the air out through your lips, as if you were trying to blow up a stiff balloon.
  • Ambulatory blood pressure and ECG recording. This test involves wearing a blood pressure cuff for 24 hours with periodic automatic recording of your blood pressure. You'll also be fitted with a monitor to allow a continuous ECG reading. You will be asked to keep a diary and to try to capture an episode of intermittent orthostatic hypotension.
Jul. 20, 2011