How to test electrolyte status (And how to correct deficiencies)

Most people are confused about electrolyte testing. If a blood test comes back within normal ranges, they think that everything is peachy.

But that’s not how it works. Electrolyte panels measure electrolytes in the blood, but they don’t tell you if you’re getting enough of a given electrolyte through diet and supplementation.

This is so important that it bears repeating. Electrolyte blood tests DO NOT assess your nutritional status for a given electrolyte.

When an electrolyte test is out of range, it means something funky is going on. I’m talking about situations like kidney failure, heart failure, medications, and illnesses that cause diarrhea or vomiting.

A diet low or high in electrolytes may contribute to an out-of-range result, but it’s rarely the primary driver. The real problem is folks taking comfort in their in-range results. It seems to suggest that electrolytes are squared away.

Can you blame people for thinking that? I can’t. Many doctors don’t explain this stuff. And some don’t even fully understand it.

In this article, I’ll do my best to clear up that confusion. You’ll learn how to assess your electrolyte status, then I’ll cover practical tips for tuning up your electrolyte game.

Electrolyte Imbalance vs. Electrolyte Deficiency

An electrolyte imbalance is not the same as an electrolyte deficiency. We need to distinguish these terms first so the rest of the article makes sense.

An electrolyte imbalance is when blood levels of a given electrolyte are too low or too high relative to some other electrolyte or mineral. It’s a nontrivial medical condition that shows up on blood tests, usually as part of a comprehensive metabolic panel.

The main causes of electrolyte imbalance include:

  • Kidney or heart failure
  • Vomiting or diarrhea from illness (which can cause potassium imbalance)
  • Diuretic medications 
  • Consuming excesses of alcohol
  • Overhydration with plain water (that may cause sodium imbalance)

You’ll see that an electrolyte-poor diet is not among these causes. That’s not an oversight. Your body is rather keen on preventing electrolyte imbalances, even when dietary intakes are low or high.

How does your body keep electrolyte levels within normal ranges? It uses the kidneys.

If sodium or potassium levels get too high, your kidneys excrete more electrolytes through urine. And when they’re too low, it slows down excretion.

It’s a fairly well-calibrated system, but it’s not perfect. For instance, if you don’t consume enough electrolytes, your body goes into electrolyte-sparing mode. You retain more sodium and potassium—and excrete more water through urine. This fluid loss can cause blood volume to plummet, but no doctor is testing for hypovolemia (low blood volume) as part of a normal test.

Your body has another way of “topping off” serum electrolytes when they fall too low. It’s a vast storehouse of minerals called the human skeleton.

Yes, your body will literally break down bone (yikes!) to keep minerals like sodium, calcium, and magnesium within normal ranges. That’s how important these elements are to normal physiologic function.

What About Electrolyte Deficiency?

An electrolyte deficiency is an inadequate dietary intake of a given electrolyte. Electrolyte deficiency won’t show up on a blood test, but it will show up in other ways. To be clear, other tests exist that can assess this status, but most insurance policies are remiss to cover them and they require a ton of doctors’ time and energy.

Electrolyte deficiencies are far more common than electrolyte imbalances. People usually don’t walk around with low serum sodium (hyponatremia), low serum potassium (hypokalemia), or low serum magnesium (hypomagnesemia) because our bodies keep our serum electrolytes in check.

And so nothing will look abnormal on a metabolic panel. But deficiencies (inadequate dietary  intakes) will prevent optimal function.

The symptoms of electrolyte deficiency are often subtle. Depending on the specific deficiency, they might present as low energy, muscle cramps, headaches, insomnia, irritability, brain fog, dizziness, or weakness.

There are also clinical signs of chronic electrolyte deficiency. Not getting enough magnesium or calcium, for instance, leads to bone density issues. And not getting enough potassium can present as high blood pressure.

Since these signs and symptoms can be driven by many other conditions, the best approach is to do a dietary analysis, figure out your daily intakes, then adjust your diet and supplement routine accordingly. I’ll review this topic after we dig into electrolyte tests.

Testing Electrolyte Status

In this section, you’ll learn how to assess your sodium, potassium, magnesium, and calcium status. It mostly involves looking at signs, symptoms, and dietary intakes.

I won’t be talking about:

  • Chloride (chloride almost always accompanies sodium in salt)
  • Phosphorus (phosphorus deficiency is rare)
  • Bicarbonate (our bodies produce their own bicarbonate)

Let’s start with sodium.

Assessing Sodium Status

A sodium blood test tells you very little. It tells you that your kidneys are working properly and that you aren’t currently hyponatremic from overhydration.

So how do you know if you need more sodium? Look at these areas:

  • Sweat loss. The more you sweat, the more sodium you’ll need. Athletes exercising in the heat can lose up to 7 grams of sodium per day.

If you identify with any of these factors, you likely need more sodium. A good evidence-based target is 5 grams per day, but some extra-sweaty folks will need 10 grams or more.

I recommend doing a dietary analysis to tabulate your current sodium intake, then adjusting from there. This basic strategy also holds for potassium, magnesium, and calcium assessment.

Assessing Potassium Status

To assess potassium status, start by logging 1-3 days of meals in an app like Cronometer. (It calculates the other electrolytes too). Your target is 4.7 grams of potassium per day.

This target (which only 3% of Americans hit) is based on evidence for potassium lowering blood pressure. This leads us to the main marker of potassium deficiency: elevated blood pressure. So if your blood pressure is high, you may be short on potassium.

But of course, low potassium is only one possible contributor to hypertension. In the case that your hypertension is not able to be managed via improvements to diet and lifestyle factors, medical care, possibly including medication, may be needed.

Other signs of potassium deficiency include:

  • Muscle cramps
  • Constipation
  • Tiredness
  • Malaise
  • Weakness

Use these symptoms along with the dietary analysis to calibrate your potassium intake.

Assessing Magnesium Status

Magnesium has many roles in the human body, and most of them are unrelated to electricity conduction. (Read: unrelated to being an electrolyte). Magnesium structures bone, repairs DNA, aids in energy production, and so much more.

As with potassium and sodium, you can’t rely on magnesium blood testing. Only 0.3% of total body magnesium is present in the blood, so it’s hard to get an accurate reading there.

The trick is to combine the two lines of evidence that we use for all these minerals:

  1. Dietary analysis
  2. Signs and symptoms

Use Cronometer to assess your daily intake of magnesium, then turn your attention to any signs and symptoms of magnesium deficiency. These might include:

  • Muscle cramps
  • Fatigue or weakness
  • High blood pressure (hypertension)
  • Increased inflammation
  • Kidney stones
  • Osteoporosis (brittle bones)
  • Cardiac arrhythmias
  • Heart palpitations

Adults need anywhere from 400 to 600 mg of magnesium per day. Based on what our ancestors consumed, I recommend shooting for the upper end of this range.

Assessing Calcium Status

Adults require about a gram of daily calcium to support bone health, muscle health, and other vital functions. And if you’re low on dietary calcium, your body will pull it from bone to maintain serum levels.

So no, a blood test doesn’t tell you much about calcium status. Talk about beating a dead horse.

Do the dietary analysis instead and modify your intake accordingly. Interestingly, when we analyzed Ketogains folks eating low-carb, whole foods diets, most of them were fine on calcium.

One last note: I’m wary of recommending calcium supplements because some evidence suggests they may increase heart disease risk. Get your calcium through your diet whenever possible.

4 Suggestions for Improving Electrolyte Status

Want to reduce your risk of electrolyte deficiencies? Follow these tips:

#1: Use the salt shaker liberally

Sodium deficiency is widespread. Active folks lose sodium through sweat, low-carb folks lose it through urine, and nobody uses the salt shaker enough.

Getting enough sodium (5 grams per day) requires consuming 2.5 teaspoons of salt. That’s a fair amount of salt shaking, so don’t be shy with it.

And no, 5 grams of sodium per day isn’t bad for your heart. According to a 2011 JAMA paper, 5 grams of sodium per day is actually the sweet spot for heart health outcomes.

#2: Eat electrolyte-rich foods

You should be getting the bulk of your electrolytes from your diet. Here are some examples:

  • For sodium: Consume salt.
  • For potassium: Consume dark leafy greens, meat, potatoes, and fruit.
  • For magnesium: Consume dark leafy greens (magnesium sits at the center of the chlorophyll molecule) and nuts.
  • For calcium: Consume dairy, bones, and cruciferous vegetables.

For a full tutorial on this topic, check out this handy guide to electrolyte-rich foods.

#3: Supplement

In an ideal world, we’d get all our nutrients from food. But due to travel, food intolerances, or the sheer weight of modern living, this isn’t always possible.

That’s where supplements come in. In addition to 5 grams of sodium, I recommend folks get about 1 gram of supplemental potassium (from potassium citrate) and about 200-300 mg of supplemental magnesium (from magnesium malate, citrate, or glycinate). This is generally sufficient to cover any dietary shortfalls.

#4: Drink electrolyte drinks

Consuming electrolytes along with fluids is a smart way to stay hydrated without diluting blood electrolyte levels. Plus it moves you closer to your daily electrolyte needs.

I formulated LMNT (my tasty electrolyte drink mix) for this exact purpose. LMNT contains the optimal doses of electrolytes—in the optimal ratios—to support energy levels, performance, and general health.

1-2 sticks of LMNT each day can be a game-changer for people with electrolyte deficiencies—especially low-carb and active folks. Energy improves, symptoms dissipate, and they feel like a Jedi.

The best part is, no blood test is required. If you’re deficient, you’ll be able to feel the difference when you finally dial in your electrolytes.

Of course I recommend LMNT, but I know that it isn’t an option for everybody. That’s why I always tell people how to make their own homemade electrolyte drinks too. Everyone should be able to get their electrolytes in check so they can get on with life, feeling and performing their best.

I encourage you to assess your electrolyte status using the steps from this blog, then correct it with foods or supplements.