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Potassium Level

Electrolytes

KK+Plasma potassiumSerum potassium

Review status

Currently under review

Pending specialist review and validation.

What it shows

The potassium level test measures the amount of potassium in the liquid part of your blood. Potassium is a key mineral and electrolyte that helps your nerves send signals, your muscles contract, and your heart keep a steady rhythm. Your body tightly regulates potassium using your kidneys and hormones such as aldosterone.

This test is commonly included in an electrolyte panel or basic metabolic panel. It is done from a blood sample taken from a vein and reflects the current balance between what you take in, what shifts in and out of cells, and what your kidneys remove.

Why it matters

Potassium levels that are too low or too high can disturb the electrical activity of the heart and muscles. Your clinician may order this test if you have symptoms like weakness, cramps, tingling, or palpitations, or to monitor conditions such as kidney disease, heart failure, high blood pressure, or diabetes. It is also checked when you are ill with vomiting or diarrhea, or before and after certain procedures.

Many medicines affect potassium, including diuretics, ACE inhibitors, ARBs, mineralocorticoid receptor antagonists, and potassium supplements or salt substitutes. Tracking your potassium helps guide safe treatment decisions, reduce the risk of rhythm problems, and identify when diet, medications, or fluids need adjustment.

Understanding your results

Your clinician will interpret your result in context, including your symptoms, medical history, kidney function, and medications. If a result is unexpected, a repeat test may be done to rule out sample issues, since problems during the blood draw or processing can falsely raise the measured value.

Low potassium, called hypokalemia, can be related to diuretics, vomiting or diarrhea, low intake, or certain hormone conditions. High potassium, called hyperkalemia, can occur with kidney problems, some medicines, severe dehydration, tissue breakdown, or shifts of potassium out of cells. Follow-up may include an electrocardiogram, changing or temporarily stopping a medication, adjusting diet or supplements, or treatment in clinic or hospital if needed. Do not change medications or diet on your own without guidance.

Reference ranges

3.96 mmol/L
All sexes
0 days – 1 month
3.66 mmol/L
All sexes
1 month – 1 year
3.25.7 mmol/L
All sexes
1 year – 5 years
3.45.4 mmol/L
All sexes
5 years – 10 years
3.55 mmol/L
All sexes
10 years – 18 years
3.55 mmol/L
All sexes
18 years – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact Potassium Level

  • Sample handling and hemolysis

    Tight tourniquet use, fist clenching, rough transport, extreme temperatures, or delays in separating serum or plasma can burst blood cells and falsely increase measured potassium.

  • Kidney function

    Your kidneys regulate potassium. Reduced kidney function, dehydration, or reduced urine output can raise potassium, while increased losses through the kidneys can lower it.

  • Medications and supplements

    Diuretics, ACE inhibitors, ARBs, mineralocorticoid receptor antagonists, heparin, trimethoprim, and NSAIDs may raise potassium, while loop or thiazide diuretics, beta agonists, and insulin may lower it. Potassium supplements and salt substitutes can also increase levels.

  • Gastrointestinal losses

    Vomiting, diarrhea, laxative overuse, or bowel drainage can reduce body potassium and lead to low blood levels, especially if fluid intake is limited.

  • Shifts between cells and blood

    Acid-base changes, severe hyperglycemia, insulin dosing, strenuous exercise, trauma, burns, or rhabdomyolysis can move potassium into or out of cells and alter the blood result.

  • Special populations and conditions

    Infants, older adults, and people on dialysis are more vulnerable to changes. Endocrine disorders such as hypoaldosteronism or hyperaldosteronism can strongly influence potassium balance.

2026

References

  1. McGill University Health Centre. (2015, July 02). Potassium Level (Task CD 317144). Laboratory reference ranges.
  2. Kidney Disease: Improving Global Outcomes (KDIGO). (2020). Hyperkalemia in chronic kidney disease: A KDIGO Controversies Conference report. Kidney International, 97(1), 42-57. https://doi.org/10.1016/j.kint.2019.09.023 External link
  3. American Heart Association. (2020). 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: Part 10: Special circumstances of resuscitation. Circulation, 142(16_suppl_2), S337–S357. https://doi.org/10.1161/CIR.0000000000000914 External link