What you need to know about POTS (Postural orthostatic tachycardia syndrome)

From the desk of
Luis Villaseñor
ScienceWhat you need to know about POTS (Postural orthostatic tachycardia syndrome)

Millions of Americans suffer from a mysterious condition called POTS, or postural orthostatic tachycardia syndrome. When someone has POTS, their heart rate rapidly increases when they stand up, causing symptoms like dizziness, brain fog, and nausea.

POTS is generally attributed to a lack of proper blood flow to the brain. The blood stays settled in the lower half of the body, the heart beats faster to compensate, and a range of symptoms result.

Beyond this general explanation, however, the precise causes of POTS are both puzzling and highly variable. In fact, POTS appears to be a group of separate disorders united only by their symptoms.

In this way, POTS is similar to IBS, or irritable bowel syndrome. The causes are many, and the diagnosis is made based on symptomatology, not underlying pathology.

Still, a handful of treatments show promise for POTS. One of these treatments, interestingly enough, is to eat more salt. Salt increases blood volume, which helps shuttle more blood and oxygen to the brain.

This article will be a brief overview of POTS: What it is, what might cause it, and the most promising treatments. I think you’ll find it interesting.

What Is POTS?

POTS stands for postural orthostatic tachycardia syndrome. Let’s take this word one word at a time:

  • Postural: Refers to the position of your body
  • Orthostatic: Refers to standing up
  • Tachycardia: Refers to rapid heart beat
  • Syndrome: Refers to a set of symptoms that characterize a condition

When you break it down like this, the nomenclature makes sense. POTS is a set of symptoms—including rapid heartbeat—that occur when someone assumes the standing posture.

POTS is a common condition, affecting anywhere from 500,000 to 3 million Americans, depending what source you look at. The condition affects women 5 times more frequently than men, and is also more likely to occur in adolescents than the general population.

The hallmark of POTS is a rapid heartbeat while standing, but a range of non-specific symptoms may also occur. These symptoms include:

  • Headache
  • Lightheadedness or dizziness
  • Brain fog
  • Exercise intolerance
  • Blurry vision
  • Heart palpitations
  • Tremors
  • Nausea

For someone with POTS, these symptoms tend to get worse with longer standing periods. Hot days, sweating, and fasting may also exacerbate symptoms due to fluid and sodium loss.

POTS Diagnosis

The gold standard for diagnosing POTS is the tilt table test. To take this test, you lie on a table that moves from horizontal to vertical, simulating the action of standing up.

The person administering the tilt table test is watching for an increase in heart rate of at least 30 beats per minute within 5 to 30 minutes of the tilt. For an adolescent to be diagnosed with POTS, the increase must be at least 40 bpm.

Alternatively, you can test for POTS by having the patient rise from the supine position, then checking for signs of tachycardia. Some researchers believe this test mimics real-world situations better than the tilt table, provided the patient stands without assistance.

A POTS diagnosis is only made after several other conditions have been ruled out. These include dehydration, a reaction to medications, and orthostatic hypotension. Orthostatic hypotension presents similarly to POTS, and is signified by a drop in blood pressure when someone stands up.

What Causes POTS?

Cerebral hypoperfusion, or reduced blood flow to the brain, is probably the biggest driver of POTS. Less blood flow, less oxygen, more symptoms.

And the triggering event is standing up.

Here’s why. When you stand, blood gets pulled away from the brain and towards the lower half of your body. To compensate, various hormones—like renin and aldosterone—are secreted to boost blood volume and deliver more blood to the upper half of your body. Your heart rate may also increase by a small amount.

But for people with POTS, this system is broken. Blood volume and blood pressure don’t rise like they should, so blood flow to the brain is restricted. And the heart responds by beating like crazy.

Why does this system break? That’s where things get hazy. There isn’t just one type of POTS, there are several. These include:

  • Hypovolemic POTS: Related to low blood volume.
  • Hyperadrenergic POTS: Related to an excess of the adrenal hormones epinephrine and norepinephrine, both of which increase heart rate.
  • Neuropathic POTS: Related to damage of the nerves that regulate blood vessels.
  • Secondary POTS: Related to some other cause, like Lyme disease, diabetes, or autoimmune disease.

But the story doesn’t end here. Going one layer deeper, low blood volume POTS may be related to low levels of aldosterone and renin, your sodium retention hormones. This has been shown in some percentage of POTS patients.

The aldosterone-renin link likely explains why many POTS patients respond favorably to increased sodium intake. Let’s get into that now.

Sodium for POTS

Sodium is an electrolyte found in salt that regulates fluid balance inside and outside your cells. Specifically, sodium increases blood volume—which has the effect of increasing blood flow throughout your body, including your brain.

Recall that many cases of POTS are associated with low blood volume, possibly driven by renin and aldosterone deficiency. The question remains: Does eating more salt improve POTS symptoms?

It appears that it does. Taking a salt tablet or electrolyte solution, research suggests, can help restore blood volume in those with hypovolemic POTS. Some physicians recommend up to 6 grams of sodium per day for this purpose.

Other research has found sodium chloride (saline) injections to be quite helpful in reducing POTS-related heart rate and blood pressure fluctuations.

I know what you’re thinking. Intravenous sodium?? I don’t have the time for or access to that.

Not to worry. Based on this study on ultra-endurance athletes, I believe that drinking a salty solution is just as effective as IV for increasing blood sodium levels. You can mix your own sodium beverage at home, or try my high-sodium electrolyte drink mix, LMNT.

Other Treatments For POTS

Along with eating more salt, increasing fluid intake can help boost blood volume and alleviate POTS symptoms. One needs to be careful, however, not to guzzle sodium-free water without proper attention to electrolytes. This can dilute blood sodium levels and make things worse.

It’s also been shown that aerobic exercises like jogging, cycling, and swimming can help with POTS. Just be sure to hydrate with fluids and salt.

Some behavioral changes may also reduce POTS symptoms. These include sleeping with your head elevated, standing with crossed legs, and avoiding long periods of standing.

Finally, a number of medications are commonly prescribed for POTS, including:

  • Beta-blockers. Beta-blockers may help POTS patients with high adrenaline, but not POTS patients with low blood pressure.
  • Fludrocortisone. This drug increases blood volume by increasing salt and water retention.
  • Erythropoietin. Erythropoietin increases blood volume and red blood cell mass.
  • Vasoconstrictors. These medications tighten blood vessels to prevent blood pooling in the lower half of the body.

If you have POTS, work with your doctor to come up with a holistic treatment plan. Some of these medications have side effects which shouldn’t be taken lightly.

POTS Summary

Here’s a quick recap of what you just learned about postural orthostatic tachycardia syndrome, or POTS:

  • Up to 3 million Americans have POTS, and the distribution skews toward adolescents and women.
  • When someone has POTS, their heart rate increases by 30 bpm after standing.
  • Other POTS symptoms include fatigue, dizziness, headache, difficulty concentrating, and nausea.
  • POTS is generally attributed to low cerebral blood flow.
  • The underlying causes of POTS may include low blood volume driven by low renin and aldosterone, high adrenaline levels, diabetes, or other conditions.
  • Increasing sodium intake, which increases blood volume, has been shown to alleviate POTS symptoms.
  • Other POTS treatments include drinking more water, exercise, behavioral changes, and several classes of drugs.

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