How Low Blood Pressure Is Diagnosed

Your doctor will diagnose you with low blood pressure using a combination of a physical examination, an investigation of your medical history, and a number of medical tests such as electrocardiogram, blood tests, echocardiogram, stress test, and tilt table test.

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Labs and Tests

Your doctor may need to perform several tests if he suspects you have hypotension.

Blood Tests

Blood tests to check your blood sugar levels and blood cell count will be performed. They will help your doctor determine if your low blood pressure is caused by low blood sugar (hypoglycemia) or anemia.

The blood test will simply involve your doctor or the lab-technician drawing some of your blood, typically from a vein in your arm.

Valsalva Maneuver

The Valsalva Maneuver is a simple test and will help your doctor evaluate if there is a problem with your autonomic nervous system, the part of your nervous system that regulates your heartbeat and how your blood vessels expand and constrict.

While your blood pressure and heartbeat are being monitored, your doctor will instruct you to take a deep breath and then try to blow out against your mouth while it’s closed, as if you're trying to blow a balloon. You may be asked to do this several times.

Tilt Table Test

Your doctor may order a tilt table test if you have complained of unexplained fainting, one of the symptoms of low blood pressure.

You will be placed on a table that has the ability to switch you from lying down to an upright position very quickly. Your body’s reaction to being switched between these two positions will be monitored with an electrocardiogram.

If you have neurally mediated hypotension (low blood pressure caused by faulty communication between the heart and the brain), you will likely faint during this test.


There are several different imaging tests that your doctor may order to help in diagnosing low blood pressure.


This test is used to check for heart problems that may cause your blood pressure to drop. An Electrocardiogram (ECG) records the heart's electrical activity and is able to detect heart structural abnormalities, irregularities in heart rhythm, heartbeat speed, and blood supply problems.

The test is non-invasive, as it simply involves the attachment of sticky patches (electrodes) to your skin on your chest, arms and legs. The patches pick up your heart’s electrical signals, while a machine records them and displays them on the screen as a graph.

Because heart rhythm abnormalities are not constant—here one minute and gone the next—your doctor may give you a "take-home" electrocardiogram device. This device is called a Holter and Event monitor. It is a small and portable device that you can wear on your body daily as it continuously records your heart activity.


An echocardiogram will, using high-frequency sound waves, obtain images of your heart and its chambers. The images show how your heart looks, its size and how well it is pumping.

This test is also non-invasive. You will be connected to an ECG machine with electrodes. The sonographer (person conducting the test) will then put a gel substance on your chest and wave a transducer (wand-like object) over the area.

Stress Test

This actually involves one or more of many tests. Your doctor will instruct you to exercise, or, if you’re unable to exercise, you’ll be given medication to make your heart pump faster.

While you are exercising, (or as the medication takes effect) your heart activity will be measured and recorded by electrocardiogram, nuclear heart scanning, echocardiogram or positron emission tomography (PET) scan.

Frequently Asked Questions

What causes low blood pressure?

Causes of low blood pressure include pregnancy, blood loss, hypothyroidism, nutritional deficiencies, low heart rate, septic shock, anaphylaxis, and certain medications, such as those used to treat depression and some heart conditions.

When does low blood pressure become an emergency?

When blood pressure drops too low, it may not allow enough blood to get to vital organs and you could go into shock. The symptoms that would indicate that blood pressure is too low and reaching this point may include nausea, heart palpitations, dehydration, fainting, blurred vision, headache, neck pain, back pain, and fatigue.

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  1. Cleveland Clinic. Low blood pressure: when to seek emergency care. Updated January 14, 2021.

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