Symptoms of low sodium (and how to treat hyponatremia)

From the desk of
Luis Villaseñor
ScienceSymptoms of low sodium (and how to treat hyponatremia)

Today I’ll be covering how to identify, prevent, and treat the symptoms of low sodium. If you’re not looking out for them, they can sneak up on you.

Inadequate sodium underlies a surprising number of health issues, but it’s often confused for something else. Let me give a few examples.

When an endurance athlete is cramping, confused, and sluggish at the end of a long race, people suspect dehydration. But more often the problem is hyponatremia, a serious medical condition of low blood sodium levels.

When a person has headaches, muscle cramps, brain fog, and weakness when starting a keto diet, people call it keto flu. The typical advice? “Give it time, it’ll pass!”

But after living la vida low-carb for a long time, and in my experience coaching thousands of clients, I understand the real cause. These symptoms are usually a case of sodium deficiency and/or electrolyte imbalances.

When someone sees unfavorable movements in blood pressure, stroke risk, and heart attack risk on a salt-restricted diet, rarely is the suggestion to bump up sodium intake. But bumping up sodium (and potassium too) is just what they need.

I’m not saying that sodium is a one-size-fits-all cure. It’s not. I’m just saying that most people—especially active people and those eating low-carb, paleo, carnivore diets—need more sodium to feel and perform their best.

Later, I’ll talk about how to avoid low sodium symptoms. First, let’s see what sodium is good for.

Why We Need Sodium

Sodium is an essential mineral. In other words, dietary sodium supports necessary physiological functions.

One of these functions is to prime a protein—an enzyme system found in the membrane of all animal cells—called the sodium-potassium pump.

The pump is extremely important. It regulates membrane potential (allowing nerve impulses to fire), brings nutrients into cells, and influences fluid balance.

The pump works by pumping sodium ions out of the cell and potassium ions into the cell. These minerals are required for these pumps to use ATP (energy) and continue powering your nervous system.

Sodium also regulates the balance of fluids throughout your body. Fluid balance is what keeps your blood moving through your blood vessels, your eyes moist with tears, your brain floating in cerebrospinal fluid, and your digestive system lubricated.

Optimal fluid balance is synonymous with optimal hydration. And you need sodium to make that happen.

What Happens When We Don’t Get Enough Sodium

If you stop consuming sodium, your body will immediately take notice. The mineral is so important that we have an array of defenses designed to hold onto it.

One of these defenses is the hormone aldosterone. Triggered by low sodium levels, the release of aldosterone tells your kidneys to reabsorb more sodium. All good, right?

Not really. Aldosterone also raises blood pressure, an effect that probably explains why very low sodium diets aren’t effective for lowering blood pressure.

Along with aldosterone, norepinephrine and epinephrine also help you retain sodium. These alertness hormones aren’t “bad” per se, but in excess, they can raise blood pressure and cause insomnia.

Yet probably the biggest danger of inadequate sodium is that it increases hyponatremia risk. Let’s talk about that.

Sodium Deficiency vs Hyponatremia

When someone talks about low sodium, they may be talking about one of two things:

  1. Low sodium intakes (sodium deficiency)
  2. Low sodium levels in the blood (hyponatremia)

By itself, sodium deficiency won’t lead to hyponatremia. Like I explained earlier, your body has an elaborate system for maintaining sodium levels. One has to be super low on sodium levels (danger territory) for blood tests to show something is wrong. This often confuses people: “My tests are ok, so why would I need more sodium?”

I mentioned a few sodium-retention hormones before, but I didn’t mention where your body scavenges sodium when sodium runs low. It scavenges it from bone. That’s right. If you’re sodium deficient, your body will actually ransack bone to keep blood levels up. That’s why low-salt diets are linked to osteoporosis.

So sodium deficiency won’t show up on a blood electrolyte panel. If your sodium levels are in range, it just indicates your sodium retention system is functioning properly.

Hyponatremia occurs when this system gets overwhelmed. The most common causes of this severe drop in blood sodium levels are:

  • Heart failure
  • Kidney disease
  • Liver disease
  • Cancer
  • Diarrhea
  • Vomiting
  • Diuretic usage
  • Excessive consumption of sodium-free water

If you are dealing with medical issues, please see a doctor about those. A savvy medical professional will understand the clinical importance of electrolytes.

But that final cause of hyponatremia—drinking too much water—is why you see so many endurance athletes staggering around in a stupor after a race. Why do they drink so much water? To prevent dehydration.

But in the misguided effort to prevent dehydration, sodium is largely forgotten.

Symptoms of Low Sodium

In mild cases of hyponatremia, a person may experience headaches, weakness fatigue, muscle cramps, or brain fog. These symptoms are similar to the symptoms of sodium deficiency.

A blurry line separates the two conditions of mild hyponatremia and sodium deficiency. Both are driven by similar factors like excessive sweating, excessive fluid intake, and inadequate sodium intake.

Dietary composition also matters. For instance, keto folks are often sodium depleted because carb restriction increases urinary sodium loss. Diuretic medications can have a similar effect.

The bottom line is that sodium deficiency and subclinical hyponatremia present similarly. Often, the symptoms are subtle. Maybe you feel “off” in the gym or can’t concentrate at work.

You might chalk it up to poor sleep or stress, and you might be right. But unless you’re consciously tracking your sodium intake, you might be dealing with a hidden electrolyte issue.

I see this all the time in active low-carb people. They’re losing sodium through multiple routes (sweat and urine) and they aren’t replacing it with the salt shaker. Then they wonder why they’re lurching through life like a tranquilized rhinoceros.

Symptoms of Hyponatremia

To be clear, this level of sodium deficiency won’t show up in the blood. Outside of medical conditions, you typically only see hyponatremia in the context of over-watering exercise.

The symptoms of moderate to severe hyponatremia include:

  • Confusion
  • Loss of consciousness
  • Seizures
  • Extreme lethargy
  • Light sensitivity
  • Brain damage
  • Brain swelling
  • Death

Exercise physiologist Dr. Tim Noakes has treated many runners with exercise-associated hyponatremia. How would he describe their symptoms?

“You become confused and very typically lose consciousness, or else as you lose consciousness you have an epileptic seizure,” Noakes is quoted as saying. “That’s the usual presentation in the advanced cases.”

The other presentation, according to Noakes, is that the person becomes “very withdrawn”. They’re slow to speak and their mind is sluggish. Due to significant swelling, their brains don’t work properly.

Fortunately, this improves rapidly when you treat the underlying sodium deficit.

How to Prevent Exercise-Associated Hyponatremia

The best way to deal with hyponatremia is to avoid developing it. Medical conditions aside, this is largely a function of proper hydration.

Healthy hydration is a big topic, but it can be boiled down to two directives:

  1. Drink to thirst. The often quoted “drink 8 glasses of water per day (some even say a gallon) is a myth!
  2. Consume sodium along with fluids. Fluids can come in various forms: whole foods such as vegetables, also have fluids in them, so they also help to hydrate you in some capacity!

Thirst is how your body signals its need for fluids. It’s a well-calibrated mechanism that rarely lets us down.

Yes, even athletes drinking to thirst and sweating excessively will experience some level of dehydration. Yet not only is this normal, but it also doesn’t appear to affect performance.

Drinking beyond thirst, however, creates an unnecessary hyponatremia risk. It’s the cause of much needless suffering.

The other pillar of hydration is to take salt along with fluids. You lose both sodium and water when you sweat, and both must be replaced for continued vitality.

Ideally, you want to be drinking a solution that mimics the osmolality (electrolyte concentration) of your blood. That’s why we put 1 gram of sodium in every stick of LMNT, our tasty electrolyte drink mix.

How To Treat Hyponatremia

Hyponatremia is a life-threatening medical condition. If possible, it should be treated in a medical setting by medical professionals.

Typically, hyponatremia is treated with intravenous (IV) saline solution, aka salt water. There’s no faster way to raise sodium levels.

The evidence suggests that oral saline solutions also work. For instance, one 2014 study found that drinking salt water effectively reversed exercise-associated hyponatremia in super-distance (161 km race) athletes.

The solution, by the way, did NOT contain glucose. Although glucose can help with sodium absorption through the gut, it’s not necessary for managing your sodium status. That’s good news for those of us limiting carbs.

Getting Enough Sodium

Getting enough sodium is an insurance policy against low sodium levels. It won’t prevent the consequences of severe overhydration, but it will prevent sodium deficiency.

Based on both anecdotal and scientific evidence I’ve reviewed, most people should shoot for 4–6 grams of sodium per day. (About 2–3 teaspoons of salt.) Active people, however, will need more to replace what’s lost through sweat. Athletes can lose up to 7 grams of sodium per day in the heat!

Me? I get the bulk of my sodium from good quality salt, and I particularly enjoy the flavor of sea salt. I also add 1 to 3 sticks of LMNT to my water each day (usually around my training sessions), depending on the intensity of my workouts.

That’s how I prevent low sodium symptoms from sneaking up on me. Feel free to steal my protocol!

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