Normal potassium level

Hyperkalemia is the medical term that describes a potassium level in your blood that's higher than normal. Potassium is a chemical that is critical to the function of nerve and muscle cells, including those in your heart.

Your blood potassium level is normally 3.6 to 5.2 millimoles per liter (mmol/L). Having a blood potassium level higher than 6.0 mmol/L can be dangerous and usually requires immediate treatment.

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Nov. 08, 2022

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Overview

What is hypokalemia?

Hypokalemia is when the amount of potassium in your blood is too low. Normal levels of potassium for an adult range from 3.5 to 5.2 mEq/L (3.5 to 5.2 mmol/L). Anything lower than 3 mEq/L (3 mmol/L) may be considered severe hypokalemia.

Potassium is an electrolyte. Electrolytes are minerals that carry an electric charge when they’re dissolved in your bodily fluids. Your body needs potassium for your cells, muscles and nerves to function correctly. Your body gets potassium through the food you eat. Your kidneys remove excess potassium through your urine (pee) to keep a proper balance of the mineral in your body.

How does hypokalemia affect my body?

You need potassium to keep your muscles, nerves and heart working well. You also need potassium for a healthy digestive system and bone health. Low levels of potassium can affect these important functions in your body. Over time, low levels of potassium in your body can cause effects such as abnormal heart rhythms, muscle weakness and even paralysis.

Symptoms and Causes

What causes hypokalemia?

Low blood potassium typically occurs because of an excessive loss of potassium in your digestive tract. This may be due to frequent vomiting, diarrhea or laxative use. Other causes of hypokalemia include:

Eating disorders, such as bulimia nervosa.
Excessive sweating (hyperhidrosis).
Alcohol use disorder.
Water pills (diuretics). Diuretics can cause too much potassium to be expelled through your pee (urine).
Other medications such as insulin, certain antibiotics and corticosteroids.
Adrenal disorders, such as primary aldosteronism and Cushing’s syndrome.
Chronic kidney disease.
Low magnesium levels (hypomagnesemia).
Certain kidney conditions, such as Bartter’s syndrome and Gitelman syndrome. Both are rare genetic kidney disorders that cause imbalances in your body.
Other conditions such as Liddle syndrome, a rare disorder that causes increased blood pressure.
Rarely, not getting enough potassium due to a poor diet.

What are the symptoms of hypokalemia?

Mild cases of low potassium may not cause any symptoms. But signs may include:

Constipation.
Heart palpitations.
Extreme tiredness (fatigue).
Muscle weakness and spasms.
Tingling and numbness.

More severe cases of low potassium may cause signs and symptoms such as:

Muscle twitches.
Muscle cramps.
Severe muscle weakness, leading to paralysis.
Low blood pressure (hypotension).
Lightheadedness or faintness.
Abnormal heart rhythms (arrhythmias).
Excessive urination (polyuria).
Excessive thirst (polydipsia).

Diagnosis and Tests

How is hypokalemia diagnosed?

Your healthcare provider will check your potassium level through a blood test. The normal potassium level for an adult ranges from 3.5 to 5.2 mEq/L (3.5 to 5.2 mmol/L). Potassium levels between 3 and 3.5 mEq/L (3 to 3.5 mmol/L) are considered mild hypokalemia. Anything lower than 3 mEq/L (3 mmol/L) is considered severe hypokalemia.

Your healthcare provider may also order a basic or comprehensive metabolic panel. This panel is a group of blood tests that determine your body's kidney function and electrolyte balance.

If hypokalemia is confirmed, your healthcare provider will try to determine the cause. If the cause isn’t clear, they may order a urine test (urinalysis) to measure the amount of potassium in your urine.

Your healthcare provider may also order an electrocardiogram (ECG or EKG). An ECG measures your heart rhythm. Hypokalemia can cause abnormal heart rhythms. An ECG can pick up the abnormal heart rhythms.

Management and Treatment

How is hypokalemia treated?

If you have a mild case of hypokalemia, your healthcare provider will prescribe a potassium supplement that you’ll take by mouth. If your case is more severe, your healthcare provider may give you potassium through your vein (intravenously). Reasons you may need potassium through your vein include:

Your potassium level is extremely low.
Hypokalemia is causing abnormal heart rhythms.
Supplements taken by mouth aren’t working.
You’re losing more potassium than can be replaced with supplements taken by mouth.

Your healthcare provider will also treat any condition that’s causing hypokalemia.

If you need to take a diuretic, your healthcare provider may switch you to a type that keeps potassium in your body. They may also tell you to take extra potassium supplements.

Prevention

How can I reduce my risk of hypokalemia?

You can reduce your risk of developing hypokalemia by eating a diet full of foods that contain potassium. Discuss your diet with your healthcare provider. Foods that contain potassium include many fruits and vegetables, lean meat and fish, dairy and legumes. Foods that have lots of potassium include:

Avocados.
Bananas.
Beans and peas.
Bran.
Dark leafy greens.
Fish.
Lean beef.
Milk.
Oranges.
Peanut butter.
Potatoes.
Spinach.
Tomatoes.

If you’re experiencing vomiting and diarrhea that lasts for more than 24 to 48 hours, you should get immediate medical care. The loss of fluid can cause hypokalemia. The sooner you seek treatment, the better your chances of preventing it.

(Note: If you’ve never had hypokalemia, prevention efforts aren’t usually necessary.)

Outlook / Prognosis

What can I expect if I have hypokalemia?

If you have a mild case of hypokalemia, potassium supplements should help treat it. Make sure to continue eating a diet rich in potassium.

If your case is more severe, potassium given through your vein should treat it. If left untreated, severe hypokalemia can cause serious heart rhythm problems. In addition, life-threatening paralysis may occur.

Be sure to follow up with your healthcare provider to ensure that your hypokalemia is treated appropriately.

A note from Cleveland Clinic

When you have hypokalemia, the amount of potassium in your blood is too low. Your body needs potassium to function correctly. Hypokalemia can affect your cells, muscles, nerves, digestive system and skeletal system. To ensure you have enough potassium, work with your healthcare provider to make sure you’re eating enough foods that contain the mineral. And if you’ve been vomiting or experiencing diarrhea for more than one to two days, get medical care right away.

Is potassium level 3.5 good?

The normal potassium level for an adult ranges from 3.5 to 5.2 mEq/L (3.5 to 5.2 mmol/L). Potassium levels between 3 and 3.5 mEq/L (3 to 3.5 mmol/L) are considered mild hypokalemia. Anything lower than 3 mEq/L (3 mmol/L) is considered severe hypokalemia.

Is a potassium level of 5.5 high?

What is a safe or normal potassium level? A typical potassium level for an adult falls between 3.5 and 5.0 millimoles per liter (mmol/L). Hyperkalemia occurs when levels go above 5.5 mmol/L. A reading above 6.5 mmol/L can cause heart problems that require immediate medical attention.

What happens low potassium?

A low potassium level can make muscles feel weak, cramp, twitch, or even become paralyzed, and abnormal heart rhythms may develop. The diagnosis is based on blood tests to measure the potassium level. Usually, eating foods rich in potassium or taking potassium supplements by mouth is all that is needed.