I want to talk about self-diagnosis of POTS, because it happens a lot. People who have been suffering with hitherto unexplained symptoms know a person with POTS, or they see something on the news or social media, and they look it up, discover their symptoms sound like POTS, and decide “Aha! This is it!”
Now, I figured out my own POTS, so I’m hardly one to criticize the idea of self-diagnosis, but we need to talk about methods. There’s a right way to do this and most people don’t go about it that way.
POTS should never diagnosed on the basis of symptoms alone (see Olshansky et al.). Symptoms can be a clue, but lots of POTS symptoms are pretty nonspecific: fatigue, lightheadedness, brain fog, general malaise, difficulty exercising. More unique symptoms are better clues, but they still are not conclusive.
The only way to a POTS diagnosis is through satisfying the diagnostic criteria for POTS. Let me walk you through the process, using my POTS as an example. I’m going to use the diagnostic criteria from Raj, Fedorowski, and Sheldon’s recent article.
POTS Diagnostic Criteria
All of the following criteria must be met:
- Sustained heart rate increase of ≥ 30 beats/min (or ≥ 40 beats/min if patient is aged 12–19 yr) within 10 minutes of upright posture.
- Absence of significant orthostatic hypotension (magnitude of blood pressure drop ≥ 20/10 mm Hg).
- Very frequent symptoms of orthostatic intolerance that are worse while upright, with rapid improvement upon return to a supine position. Symptoms vary between individuals, but often include lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision and fatigue.
- Symptom duration ≥ 3 months.
- Absence of other conditions that could explain sinus tachycardia.
Great. Let’s take these one by one.
Sustained heart rate increase of ≥ 30 beats/min (or ≥ 40 beats/min if patient is aged 12–19 yr) within 10 minutes of upright posture.
This is the orthostatic tachycardia part of Postural Orthostatic Tachycardia Syndrome. By definition, you cannot have POTS without it. If you have no idea what your heart rate is doing when you go from lying or sitting to prolonged standing, you’re missing the most important piece of information.
I’m well over 19, so the threshold for me is 30 bpm.
While we were still isolating and trying not to go anywhere during the pandemic, a lot of the “noise” of daily living went away, and I was able to notice some pretty intense heart rate spikes on my fitness watch, just from doing household chores.
I am not a fainting risk, so it was safe for me to do a poor man’s tilt test. I set my watch to Workout mode. I lay down for 10 minutes, then got up and stood stock still for another 10 (15, really), trying to recruit my leg muscles as little as possible. Here’s what this looked like:
I don’t think I noticed it at the time, but my Scanwatch recorded 31 seconds of Intense activity. From merely standing still.
You can see that my heart rate at the beginning is maybe around 75 bpm. There’s a little jump at 10 minutes when I first stand up — this is a normal compensation for gravity and a change in posture — and then it normalizes for a moment, as it should — the new normal for non-POTS people is typically a little higher than resting, but not by much. But then my heart rate starts climbing. This is distinctly not normal. My body is struggling to keep blood going to my head, so it’s revving up to compensate. By the end, I’m periodically touching the line marked 109, a roughly 35-point increase. No doubt the difference would be even more profound on a formal tilt table test. In spotchecks, I would also often see an increase from 70-80 seated to 120 bpm just standing in the kitchen, doing meal prep.
So, I’ve satisfied the first part of the diagnostic criteria: I most def have orthostatic tachycardia.
Next up:
Absence of significant orthostatic hypotension (magnitude of blood pressure drop ≥ 20/10 mm Hg).
Yeah, no. My blood pressure had started to always measure a little high, and higher on particularly symptomatic days. I never measured it while standing, of course — you can’t do that on the machines at the pharmacy — but it turns out mine increases significantly on standing and takes a while to come back down when I sit. You may need your doctor’s help to determine this if you don’t already have a home blood pressure monitor.
(It’s important to note here that orthostatic hypotension is both a diagnostic label and a descriptor. In the diagnostic criteria for POTS, they are referring to the diagnostic label of classic, sustained orthostatic hypotension, which has its own very specific diagnostic criteria, and can also cause orthostatic tachycardia. If orthostatic hypotension and orthostatic tachycardia are present and simultaneous, then we ought to assume the former is causing the latter, treat it, and see if the orthostatic tachycardia also resolves. There are other orthostatic reductions in blood pressure — a transient initial orthostatic hypotension that quickly resolves, and a delayed orthostatic hypotension that comes on later — that do not preclude a POTS diagnosis.)
Zero orthostatic hypotension — check.
Very frequent symptoms of orthostatic intolerance that are worse while upright, with rapid improvement upon return to a supine position. Symptoms vary between individuals, but often include lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision and fatigue.
This criterion can be a bit tricky, as we may not say “Aha! This happens when I am standing!” until we see the criteria and think about it. I knew when I was “active” I was having trouble. I would get winded just washing the dishes (shortness of breath) or doing meal prep, and had to sit down and take breaks. Walking the dog was easier, though I didn’t notice the discrepancy at the time. This shortness of breath I experienced standing in the kitchen was an orthostatic symptom, not a sign that I was out of shape. Nowadays, medicated, that symptom is less prominent. I’ve also experienced the whooshiness that comes with presyncope (feeling like I am going to faint), lightheadedness, and dependent acrocyanosis (legs that turn purple on standing). “Syncope is not a criterion,” say Olshansky et al., so it doesn’t matter that I don’t faint. I also experience increased agitation the longer I stay standing, specifically because I have hyperadrenergic POTS.
Symptom duration ≥ 3 months.
LOL, yes. I’ve had POTS symptoms for over a decade, but I can track some back as far as adolescence; my legs would turn purple and itch and burn as I stood washing dishes. I was also a high-strung kid and a raw nerve as a young adult; it’s no surprise I now have hyperadrenergic POTS.
And finally. . .
Absence of other conditions that could explain sinus tachycardia.
This is where self-diagnosis fails. This is where you need to see a doctor to order you preliminary bloodwork to rule out the usual suspects like anemia, as well as getting cardiac and possibly lung testing. With my symptom of shortness of breath and asthma, I had both. To check the integrity of the heart itself, it’s typical to have an echocardiogram (essentially an ultrasound of the heart), and a Holter monitor (essentially an ECG machine that you walk around wearing for a period of time to rule out problems with heart rhythms). Often all of this testing will come out completely normal, which may puzzle your doctors. Often, the only place POTS shows up in formal medical testing is on some version of a tilt test or active stand test to compare lying and standing heart rates and blood pressures. This will also differentiate POTS from other forms of orthostatic intolerance, like orthostatic hypotension.
So, it’s possible to develop a very reasonable suspicion on your own that you have POTS, but you cannot for sure know you have POTS without going through the diagnostic process. Some of the conditions that can mimic POTS are dangerous; you want to know if you have these so you can get them treated and monitor them. Many lifestyle interventions for POTS are fairly harmless, but increasing salt warrants caution. And you likely won’t be able to access the various POTS medications until you have a diagnosis.