Part 3: Is it POTS? POTS vs. OH
- Sarah Schafer, MD
- Jun 18, 2022
- 4 min read
Updated: Mar 18
Updated 10-28-2024
This page is Part 3 of a 4-part series
Part 2: Is it POTS? Autonomic mimics Part 3: Is it POTS? POTS vs. OH
Postural orthostatic tachycardia syndrome (POTS) and orthostatic hypotension (OH) can look a lot alike but are not the same thing. They both cause rapid heart rate (hr) and lightheadedness with prolonged standing. If you have OH, by definition, you don't have POTS, and vice versa. However, POTS and OH can change over time. This is why ongoing clinical assessment is helpful for guiding treatment.
I highly recommend this 16-minute video interview of Dr. Peter Rowe, where he describes how reduced blood flow to the brain produces the many symptoms of OH and POTS.
Management of POTS and OH is similar. Medication options overlap, but there are differences. While POTS is common in Sjogren’s, it is important to rule out mimics other than OH, as reviewed in Part 1 and Part 2 of this blog series.
On Sjogren’s Advocate, OH refers to a long-term difficulty maintaining blood pressure when upright because of a malfunctioning autonomic nervous system. Clinicians often think of the OH as the acute version that is seen with dehydration, blood loss, etc. It is important to explain the chronic nature of your symptoms to your clinician, and lack of response to adequate hydration.
POTS vs OH can be determined by a standing test or a tilt table test. See Part 2 of this blog series to learn the diagnostic criteria for POTS and OH.
Standing test – It is useful to document readings from two or more home standing tests before your medical appointment. Readings that support a POTS or OH diagnosis should prompt further investigation. The standing test should be repeated in the clinic setting for confirmation and documentation. See Part 2 of this blog series for the diagnostic criteria for POTS and OH. Take these to your clinic appointment:
Your standing test results The standing test handout and article recommended on the POTS page This article about OH
Even if your clinician is familiar with POTS and OH it is good to have articles on hand for self-advocacy. See the Clinician Handouts for tips about sharing articles and handouts with clinicians.
The standing test handout is for POTS. Does it work for OH?
Yes, the instructions are the same, with additional readings indicated below.
If you are doing this on your own, I recommend starting with the standing test for POTS first. If your blood pressure (bp) falls more than 10 mm systolic or 5 mm diastolic at the 2-minute mark, take a break and start over with the standing test for OH. This is the same test but requires additional early readings.
The standing test for OH
Use the standing test for POTS. Record readings at 1, 2, 3, 5, and 10 minutes (vs. 2, 5, 10 minutes.)
If your blood pressure (bp) drops more than 20 mm systolic (top number) or 10 mm diastolic (bottom number) at 3 minutes, this indicates OH, rather than POTs. It is best to complete the 10-minute test unless you feel like fainting, in which case you should stop immediately.
Why not add the extra readings for OH at the outset? This should be fine if you have someone helping you. Even small movements, such as looking at the blood pressure monitor or recording your result, reduce the accuracy of the test.
Voice recording apps are also a good option so that you can avoid writing if you are testing on your own.
TIPS
For both OH and POTS, carefully follow the instructions for the POTS standing test (see link above). Failing to do so reduces test accuracy.
Record the results, including date and time of day, along with any symptoms you have during the test.
Repeat the test on two or three additional days, without special measures such as drinking extra fluids and electrolytes prior to testing or wearing compression garments.
POTS and OH screening tests are more likely to be positive first thing in the morning.
What if you have symptoms but your standing test results fall short of the criteria for POTS or OH diagnosis?
One option is to arrange for a Tilt Table test. This eliminates the problem of involuntary leg muscle contraction interfering with test accuracy. This is test is not always readily available. Some people have symptoms that look like POTS or OH presentation but do not meet the diagnostic criteria. Orthostatic cerebral hypoperfusion syndrome (OCHOS) has been recognized as a cause of orthostatic intolerance. Most clinicians do not have access to tools to diagnose this by measuring cerebral blood flow (how much blood goes to your brain), but this may be changing soon. Non-specific causes of orthostatic intolerance may be managed similarly to POTS and OH, based on clinical judgment.
