POTS test: how POTS is measured, and what blood tests add

POTS stands for postural orthostatic tachycardia syndrome. The Heart Rhythm Society's 2015 consensus statement describes three parts: frequent symptoms on standing, such as lightheadedness, palpitations, tremulousness, weakness, blurred vision, exercise intolerance and fatigue; a sustained heart-rate rise of at least 30 beats per minute within 10 minutes of standing or head-up tilt, or at least 40 at ages 12 to 19; and no orthostatic hypotension, a fall in systolic blood pressure of 20 mm Hg or more (HRS, 2015).

A POTS test checks the second and third parts. Clinicians use two methods:

• The active stand test. You lie down for a set time, then stand while a clinician records heart rate and blood pressure at intervals. It needs little equipment.
• The tilt table test. A table tilts you upright while you lie strapped to it, so your leg muscles do less of the work. A European consensus sets the minimum equipment as a tilt table, continuous beat-to-beat blood-pressure monitoring and at least one ECG lead, and notes that tilt testing adds to the history and cannot replace it (EFAS consensus, 2021). Our guide to the tilt table test and what it measures covers the procedure.

A home heart-rate log helps at an appointment, and a clinician needs to measure blood pressure alongside heart rate and read the pattern. Our piece on POTS testing at home explains what home data can and cannot do. The patient organisation Dysautonomia International is a plain-language reference on both tests.

POTS is a form of dysautonomia, a disorder of the autonomic nervous system, which runs heart rate and blood pressure without conscious effort (Dysautonomia International). On standing, gravity pulls blood toward the legs and abdomen. In POTS the heart rate climbs more than expected in response, and symptoms follow (HRS, 2015).

Researchers study several possible drivers, and immune activity is one of them. In a group of people with POTS who carried autoantibodies against adrenergic receptors, researchers found five of ten measured cytokines and chemokines raised, including IL-1β, TNF-α and IFN-γ (Gunning et al., 2021). Findings like this describe a subgroup, and no single mechanism explains POTS in everyone.

POTS can appear after infection. The 2024 National Academies definition of long COVID names POTS among the diagnosable conditions that can make up long COVID (NASEM, 2024). Our articles on POTS symptoms and inflammation and dysautonomia and chronic inflammation go further into the immune research.

Blood tests in a POTS workup rule other causes in or out. A 2019 review in the Cleveland Clinic Journal of Medicine lists a complete blood count with hematocrit to look for anemia, TSH to look for an overactive thyroid and an electrolyte panel, with a 12-lead ECG to look for an arrhythmia (CCJM, 2019). These results matter: a fast heart rate from anemia or thyroid disease needs a different plan.

None of these tests confirms POTS, and none reads immune signalling. A normal blood count and thyroid result tell you that those explanations are less likely. They say nothing about the cytokines and chemokines that research has examined in POTS subgroups. Our overview of dysautonomia testing places the blood tests beside the autonomic ones.

A broad panel reads immune proteins a POTS workup leaves out: cytokines such as IL-1β, TNF-α and IFN-γ, the three raised in the POTS subgroup above, interferon-induced chemokines such as IP-10, and markers of blood-vessel activity such as sICAM-1 and VEGF-A. The panel places each against a healthy reference, and a retest shows which way each moves. Read beside a heart-rate log and your symptom history, that gives you and your autonomic specialist another layer of objective data.

The limits are firm. A blood panel cannot diagnose POTS, stand in for the active stand or tilt table test, or choose a treatment. A raised cytokine in a research subgroup says nothing about you on its own.

Mune Mirror™^* is currently in development, and the performance characteristics of this test have not yet been established. It is investigational. It does not diagnose, detect, screen for, treat, cure or prevent any disease. Results are for research and informational purposes, to discuss with your own doctor.

The guide to unwellness testing explains how this kind of measurement fits beside standard care.

Mune Mirror™ measures more than 1,000 immune and inflammation proteins from an at-home sample and benchmarks each against a healthy reference. For someone with POTS, or with POTS-like symptoms and normal blood work, it adds an immune record to the heart-rate and blood-pressure data your clinician collects. It does not diagnose POTS.

Can a blood test diagnose POTS?

No. Clinicians diagnose POTS from the heart-rate and blood-pressure response to standing or head-up tilt. Blood tests look for other explanations such as anemia, an overactive thyroid or electrolyte problems, and no blood marker confirms POTS.

Who should ask about a POTS test?

People with frequent symptoms on standing, such as lightheadedness, palpitations, blurred vision or fatigue, can ask their doctor whether an active stand or tilt table test fits their situation. A heart-rate log from home makes that conversation easier.

Can I do a POTS test at home?

You can record your heart rate lying down and then standing with a home monitor, and log your symptoms, which helps at an appointment. A formal test needs blood pressure measured alongside heart rate and a clinician to read the pattern, through an active stand test or a tilt table test.

What is the difference between an active stand test and a tilt table test?

In an active stand test you stand up on your own while a clinician records heart rate and blood pressure. In a tilt table test a table tilts you upright while equipment records continuous blood pressure and an ECG, so your leg muscles do less of the work. Both look for the same heart-rate response.

What heart rate counts as POTS?

The 2015 Heart Rhythm Society criteria describe a sustained rise of at least 30 beats per minute within 10 minutes of standing or head-up tilt, or at least 40 at ages 12 to 19, with symptoms on standing and without orthostatic hypotension. A clinician makes the diagnosis.

Is POTS linked to long COVID?

The 2024 National Academies definition of long COVID names POTS among the diagnosable conditions that can make it up. POTS was a recognised diagnosis before COVID-19, and it occurs in people without long COVID.