What Are High, Low and Normal Potassium Levels?

Bananas are a good source of potassium.
Image Credit: Nanette_Grebe/iStock/Getty Images

Potassium is an essential mineral that helps your heart and kidneys function at their best. But if your potassium balance is out of whack, it can take a toll on your health — that's why maintaining normal potassium levels is important for your overall wellbeing.

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Besides supporting your heart and kidneys, potassium also helps with the following functions, according to the University of Michigan Health:

  • Muscle contraction
  • Nerve transmission
  • Maintaining fluid balance
  • Maintaining normal blood pressure

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You can support a normal potassium level range by getting the nutrient naturally from the following potassium-rich foods:

  • Fruits like kiwi, bananas and melons
  • Dark, leafy greens
  • Root vegetables like squash and potatoes
  • Fish like salmon and tilapia

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Still, it's possible to have low or high amounts of potassium in your blood (conditions called hypokalemia and hyperkalemia, respectively). If you have a potassium imbalance, it's important you're under the care of a medical professional, as these conditions can be dangerous and potentially even life-threatening.

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To help you determine if your potassium is in a normal range, here's a breakdown of low, normal and high levels of the nutrient.

Low, Normal and High Potassium Levels

Severe hypokalemia

Less than 2.5 mmol/L

Moderate hypokalemia

2.5 to 3 mmol/L

Mild hypokalemia

3 to 3.4 mmol/L

Normal

3.5 to 5.0 mmol/L

Mild to moderate hyperkalemia

5.1 to 6.0 mmol/L

Severe hyperkalemia

Greater than 6.0 mmol/L

Source: StatPearls. (2020). "Hypokalemia"; National Kidney Foundation. "Potassium and Your CKD Diet"

Normal Potassium Levels

So, what is a normal potassium level in your blood? Typically, 3.5 to 5.0 millimoles per liter is considered normal, according to the National Kidney Foundation (NKF).

If you don't have any diseases that affect your average potassium level, then you can maintain a normal balance by getting your fill of high-potassium foods, per the University of Michigan Health.

Here's the recommended daily amount of potassium for adults without underlying conditions, per the 2020-2025 Dietary Guidelines for Americans:

  • People assigned female at birth:​ 2,600 mg
  • People assigned male at birth:​ 3,400 mg

Warning

Potassium supplements are also available on the market, but they can cause dangerously high potassium levels even in healthy people, per the National Institutes of Health's Office of Dietary Supplements (ODS). Accordingly, don't take them unless your doctor prescribes it.

High Potassium Levels

Potassium elimination happens naturally when your body excretes excess mineral through your urine, according to the ODS.

However, the mineral can build up in your system if you have any of the following conditions, per the ODS:

  • Type 1 diabetes
  • Kidney disease
  • Liver disease
  • Congestive heart failure
  • Adrenal insufficiency
  • You're taking certain medications (like ACE inhibitors or certain diuretics), high doses of potassium supplements or salt substitutes

But what does high potassium in your blood mean? It can lead to a condition called hyperkalemia, which is when your potassium level rises above 5.0 to 5.5 millimoles per liter, according to a January 2022 StatPearls article.

Here's a breakdown of the different degrees of hyperkalemia, per the NKF:

  • Mild to moderate hyperkalemia:​ 5.1 to 6.0 mmol/L
  • Severe hyperkalemia:​ Greater than 6.0 mmol/L

Extremely high potassium levels can be fatal: They can cause an irregular heartbeat or heart attack that requires immediate medical attention, according to the NKF.

But what if you have a potassium level of 5.4 — what does that mean? While this number is below the severe hyperkalemia threshold, it's still cause for concern: Potassium levels of 5.1 to 6.0 millimoles per liter put you in the "caution" zone, and you should take action to lower them back into the normal range, per the NKF.

Similarly, potassium levels of 5.6, 5.8, 5.7 and so on should all be addressed to prevent severe hyperkalemia.

Mild hyperkalemia may not have any symptoms, according to StatPearls. But per the Cleveland Clinic, more extreme cases can cause symptoms like:

  • Abdominal pain
  • Diarrhea
  • Chest pain
  • Irregular, fast or fluttering heartbeat
  • Muscle weakness
  • Numbness in limbs
  • Nausea
  • Vomiting

How to Treat Hyperkalemia

If you do end up being diagnosed with hyperkalemia, there are many treatments available. Per the NKF and a March 2016 study in the ​Kidney International Journal​, common options include:

  • Diuretics, which can help your kidneys produce more urine and excrete more potassium
  • Potassium binders, which help your body excrete potassium via the gastrointestinal tract
  • Dialysis, which is generally reserved for emergency situations
  • Starting a low-potassium diet and limiting potassium-rich foods

Low Potassium Levels

On the other hand, you can have too little potassium in your system, a condition called hypokalemia, according to the Cleveland Clinic. This is when your potassium levels dip below 3.5 millimoles per liter.

Here are the different degrees of hypokalemia, according to a January 2022 StatPearls article:

  • Mild hypokalemia:​ 3 to 3.4 mmol/L
  • Moderate hypokalemia:​ 2.5 to 3 mmol/L
  • Severe hypokalemia:​ Less than 2.5 mmol/L

If you have severe hypokalemia, seek medical attention right away.

And even if you have mild hypokalemia — with a low potassium level of 3.0, 3.1 or 3.2, for instance — you should still talk to your doctor to determine the best way to climb back into the normal range. While, say, a 3.1 potassium level isn't immediately dangerous or life-threatening, you'll still want to get your mineral balance back in check.

Hypokalemia can occur when too much potassium is eliminated from your body for the following reasons:

  • Frequent vomiting or diarrhea
  • Excessive sweating
  • Drinking too much alcohol
  • Medications like diuretics, antibiotics and corticosteroids
  • Low potassium intake
  • Adrenal disorders
  • Kidney disease
  • Rare disorders like Liddle syndrome, Bartter's syndrome and Gitelman syndrome

Per the Cleveland Clinic, symptoms can include:

  • Muscle twitches
  • Muscle cramps or weakness
  • Muscle paralysis
  • Abnormal heart rhythms
  • Kidney problems

How to Treat Hypokalemia

If you have hypokalemia, it's important to restore normal potassium levels. How you manage this condition depends on the cause and your blood levels. Mild hypokalemia, for instance, can be treated by eating potassium-rich foods, per the Cleveland Clinic.

Here are some other potential solutions your doctor may recommend:

  • Potassium supplements
  • Intravenous solutions
  • If an underlying disease caused hypokalemia, get treatment for that condition

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