Testing for POTS (postural orthostatic tachycardia syndrome) centers on one core measurement: whether your heart rate rises by 30 or more beats per minute within 10 minutes of standing up, without a significant drop in blood pressure. For adolescents aged 12 to 19, the threshold is higher, at 40 beats per minute. This can be measured in a clinic with a simple standing test or with a more formal tilt table test, but most people also need bloodwork and cardiac monitoring to rule out other conditions that mimic POTS.
The Core Diagnostic Criteria
POTS is not diagnosed by a single test. It’s a clinical diagnosis based on a pattern: chronic symptoms of orthostatic intolerance (dizziness, lightheadedness, brain fog, palpitations, or near-fainting when upright) lasting at least six months in adults, or at least three months in children, combined with a measurable heart rate spike upon standing.
The key numbers are specific. In adults, your heart rate must increase by at least 30 beats per minute within 10 minutes of moving from lying down to standing. In patients aged 12 to 19, the increase must be at least 40 bpm, because healthy younger people naturally have a larger heart rate response to standing. Crucially, your blood pressure must not drop substantially. A drop of more than 20 mm Hg systolic or 10 mm Hg diastolic in the first three minutes of standing points toward orthostatic hypotension instead, which is a different condition with different treatment.
The Active Standing Test
The simplest version of POTS testing can happen in a doctor’s office. You lie flat for several minutes while your heart rate and blood pressure are recorded. Then you stand up and stay still while those measurements are taken repeatedly over 10 minutes. If your heart rate climbs past the threshold and you develop your typical symptoms, that’s strong evidence for POTS.
You can also do a rough version of this at home to bring data to your appointment. Lie flat for five minutes, record your resting heart rate, then stand quietly and check your heart rate at 2, 5, and 10 minutes. A consistent spike of 30 or more bpm that’s accompanied by your usual symptoms is worth showing your doctor. Home readings won’t confirm a diagnosis on their own, but they give your provider useful information and can speed up the process.
The Tilt Table Test
A tilt table test is the more formal, controlled version of the standing test. You lie on a motorized table and are strapped in securely. After a resting period, the table tilts upward to roughly a 70-degree angle, putting you in a near-standing position without requiring you to use your leg muscles to balance. You stay tilted for up to 45 minutes while your heart rate, blood pressure, and symptoms are continuously monitored.
The advantage of the tilt table is precision. Because you’re not shifting your weight or tensing your muscles, the test isolates your cardiovascular system’s response to gravity. It also catches people who might faint during the test in a safe, controlled setting. Not everyone with suspected POTS needs a tilt table test. If the in-office standing test clearly shows the heart rate pattern and the clinical picture fits, some providers will diagnose without it. But if results are borderline or symptoms are unusual, the tilt table provides a clearer answer.
Tests That Rule Out Other Conditions
Before confirming POTS, your doctor will likely want to exclude structural heart problems and other causes of a fast heart rate. This typically starts with an electrocardiogram (ECG), a quick, painless recording of your heart’s electrical activity. Research suggests that a notable proportion of people with POTS symptoms also have underlying cardiac arrhythmias beyond simple fast heart rate, so if you have significant palpitations or chest pain that don’t seem fully explained by POTS alone, your doctor may order ambulatory rhythm monitoring. This involves wearing a portable heart monitor (often called a Holter monitor) for 24 to 48 hours, or sometimes longer, to catch irregular rhythms that come and go.
Standard bloodwork is also part of the workup. Your provider will typically check thyroid function, blood counts, and markers of dehydration or anemia, all of which can cause a fast heart rate on standing and need to be excluded before a POTS diagnosis sticks.
Autonomic Nervous System Testing
Some specialists go beyond the basic heart rate and blood pressure measurements to evaluate how well your autonomic nervous system is functioning overall. One common test is the QSART, which measures how your sweat glands respond to a mild electrical stimulus applied to the skin. Small capsules are placed on your forearm, leg, and foot, and the test records how long it takes for sweating to begin, how much sweat you produce, and when production peaks.
The QSART doesn’t diagnose POTS directly, but it can reveal whether the nerves controlling involuntary functions like sweating are damaged. This matters because a subset of POTS cases are driven by small fiber neuropathy, where the tiny nerve fibers that regulate blood vessel tone and sweating are impaired. Identifying this pattern can change your treatment approach and sometimes points toward an underlying cause, such as an autoimmune condition or diabetes.
How to Prepare for Testing
What you eat, drink, and take before autonomic testing can skew results significantly. Stanford Health Care’s autonomic testing guidelines offer a useful baseline: stop aspirin, ibuprofen, and acetaminophen 24 hours before testing. Over-the-counter sleep aids and cold or flu medications should be avoided for 72 hours, and medical marijuana for at least three days.
You do not typically need to stop anti-seizure medications, antidepressants, immunosuppressants, thyroid medications, or hormonal medications. However, some prescription drugs that directly affect heart rate or blood pressure, like beta-blockers, may need to be paused. Your provider should give you a specific list. Bring any held medications with you to your appointment so you can resume them immediately after.
Hydration and food matter too. Dehydration alone raises standing heart rate, which could exaggerate results, while eating a large meal can redirect blood flow to the gut and affect the test in the opposite direction. Most testing centers will ask you to eat a light meal a few hours before and drink water normally, but not excessively. Caffeine and alcohol are best avoided the day before and the day of testing, since both affect heart rate and blood vessel behavior.
What Happens After Testing
If your results meet the diagnostic criteria, the next step is usually identifying which subtype of POTS you have, because treatment varies. Some people have a form driven by excess adrenaline (identified partly by measuring norepinephrine levels in blood drawn while lying down versus standing). Others have a form linked to low blood volume, poor blood vessel constriction, or nerve damage. Your test results, especially the autonomic testing and bloodwork, help your provider sort this out.
If your heart rate increase is close to the threshold but doesn’t quite meet it, that doesn’t necessarily mean nothing is wrong. Some people with orthostatic intolerance fall just below the cutoff, especially if they were well-hydrated on the day of testing or had recently taken a medication that blunted their heart rate response. In those cases, your provider may repeat testing under different conditions or focus on treating your symptoms regardless of whether you technically meet the formal definition.