Potassium Levels: Normal Range & What Causes High or Low Levels

Potassium levels are important to keep within normal ranges, as this mineral is very important for proper functioning in the body. This mineral works directly on the nervous, muscular and cardiac systems and also influence pH levels in the blood. 

Having high or low potassium levels can trigger several symptoms and health conditions, from lethargy to palpitations and fainting. 

Potassium levels are often tested if symptoms arise for no apparent reason, as they can help to confirm or rule out specific diagnoses and guide treatment. 

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Normal potassium levels

Normal potassium levels are usually between 3.5 mEq/L and 5.5 mEq/L.

High or low potassium levels can lead to varying complications, as outlined below.

High potassium

High potassium levels is also called hyperkalemia.

Mildly high potassium levels will usually not cause any significant symptoms, but very high potassium levels can lead to symptoms like a low heart rate, palpitations, muscle weakness, numbness and vomiting.

What causes high potassium?

The main causes of high potassium are:

  • Kidney failure
  • Type 1 diabetes
  • Use of diuretic medications
  • Large bleeds or hemorrhages

The underlying cause is diagnosed through complementary tests, like additional bloodwork, arterial blood gas or an ECG.

Treatment options

Mild hyperkalemia can be treated by removing foods that are high in potassium from the diet.

In more serious cases, hospital admission for IV medication may be needed to correct imbalances. 

Low potassium

Low potassium levels are also known as hypokalemia. It is usually related to dehydration and excessive fluid losses from vomiting, diarrhea or increased urine output.

People with low potassium levels will typically experience symptoms such as weakness, fatigue, muscle cramps, tingling, numbness, cardiac arrhythmia and abdominal distension.

What causes high potassium?

The main causes of low potassium are:

  • Use of medications such as insulin, salbutamol or theophylline
  • Persistent vomiting or diarrhea
  • Hyperthyroidism
  • Hyperaldosteronism
  • Chronic use of laxatives
  • Cushing's syndrome

Additionally, more rarely, low potassium can occur due to nutritional deficiencies.

The underlying cause is usually diagnosed through bloodwork, urine tests, an ECG or arterial blood gas tests.

Treatment options

Treatment for low potassium depends on the cause, the patient's symptoms and the actual potassium level. It typically involves taking oral potassium supplements and consuming potassium-rich foods.

In more serious cases, IV potassium may be necessary.