The short answer
Potassium keeps your nerves, muscles and heartbeat working, so your kidneys hold its level in a narrow range.1 A normal result is 3.5 to 5.2 mmol/L.4
Check your result
Type the number from your report. It stays on this page.
- Very low Under 2.5
- Low 2.5 to 2.9
- Mildly low 3.0 to 3.4
- Normal 3.5 to 5.2
- Mildly high 5.3 to 5.9
- High 6.0 to 6.4
- Very high 6.5 or more
Enter your result to see what it means and what to do next.
Got a result from another lab? Ask Picardo about it. The app explains your results, and a physician can follow up.
Grades from European resuscitation and UK kidney guidelines, which start high potassium at 5.5.2,3 Labcorp flags anything over 5.2, so 5.3 to 5.4 is high only by its range.4 The bar isn’t to scale.
Very low: go to an emergency department today
Below 2.5, low potassium is severe. It can cause muscle weakness and dangerous heart rhythms, especially if you have heart disease or take digoxin.3
Go to an emergency department today, and right away if you have palpitations, chest pain or new weakness. Severe low potassium is usually treated through a drip.3
- 1 Take a list of your medicines with you.
- 2 Ask for your magnesium to be checked too. Low magnesium makes low potassium harder to correct.3
Low: see a clinician soon
This is moderately low.3 Low potassium is linked to dangerous heart rhythms, and the risk rises the lower it goes.1,3
See a clinician in the next day or two. If you feel weak or your heart is racing or skipping beats, go to an emergency department now. With symptoms, low potassium counts as severe.3
- 1 Review your medicines with a clinician. Water pills are a common cause.1
- 2 Check your magnesium too.3
Mildly low: find the cause
This is mildly low.3 It’s most often from a water pill, or from losing fluid with vomiting or diarrhea.1
Not urgent. Worth sorting out over the next few weeks.
- 1 If you take a water pill, ask whether your dose or medicine should change.1
- 2 If you have high blood pressure too, ask about a test for high aldosterone. It’s common in people with both.6
- 3 Check your magnesium.3
Normal
Your potassium is in the normal range.4
Nothing to worry about.
- 1 If you take an ACE inhibitor, an ARB or spironolactone, keep up your regular checks.2
Mildly high: recheck it first
A high result is often a sample problem. Potassium leaks out of blood cells if you clench your fist during the draw, the draw is difficult or the sample is slow to reach the lab.1,2,4 If it’s real, the usual causes are kidney disease and medicines that make your body hold on to potassium.2 UK and European guidelines only call it high from 5.5.2,3
Not urgent if you feel well. Get it rechecked within a few days.2
- 1 Repeat the test within 3 days, and keep your hand relaxed during the draw.1,2
- 2 Don’t stop a blood pressure or heart medicine on your own. Ask the clinician who prescribed it.2,5
- 3 Stop over-the-counter potassium supplements and potassium-based salt substitutes until it’s sorted out. Ask before stopping prescribed potassium.2
High: get it rechecked today
This is moderately high.2,3 It may still be a sample problem, but it needs checking quickly, because high potassium can upset your heart rhythm.1,2
Get it rechecked today. If you feel unwell or weak, or have palpitations, go to an emergency department now.1,2
- 1 Call the clinician who looks after your medicines today.
- 2 Stop over-the-counter potassium supplements and potassium-based salt substitutes.2
Very high: go to an emergency department
At 6.5 or higher, high potassium is severe and can cause dangerous heart rhythms. Guidelines advise immediate hospital assessment, even though a sample problem is still possible.2,5
Go to an emergency department now.
- 1 Take this result and a list of your medicines with you.
What is a normal potassium level?
Labcorp’s range for adults is 3.5 to 5.2 mmol/L.4 Outside it, guidelines grade potassium by how far it has moved, because the risk to your heart rhythm grows with it:1,2,3
Very low: go to an emergency department today
Below 2.5, low potassium is severe. It can cause muscle weakness and dangerous heart rhythms, especially if you have heart disease or take digoxin.3
Go to an emergency department today, and right away if you have palpitations, chest pain or new weakness. Severe low potassium is usually treated through a drip.3
- 1 Take a list of your medicines with you.
- 2 Ask for your magnesium to be checked too. Low magnesium makes low potassium harder to correct.3
Low: see a clinician soon
This is moderately low.3 Low potassium is linked to dangerous heart rhythms, and the risk rises the lower it goes.1,3
See a clinician in the next day or two. If you feel weak or your heart is racing or skipping beats, go to an emergency department now. With symptoms, low potassium counts as severe.3
Mildly low: find the cause
This is mildly low.3 It’s most often from a water pill, or from losing fluid with vomiting or diarrhea.1
Not urgent. Worth sorting out over the next few weeks.
Normal
Your potassium is in the normal range.4
Nothing to worry about.
- 1 If you take an ACE inhibitor, an ARB or spironolactone, keep up your regular checks.2
Mildly high: recheck it first
A high result is often a sample problem. Potassium leaks out of blood cells if you clench your fist during the draw, the draw is difficult or the sample is slow to reach the lab.1,2,4 If it’s real, the usual causes are kidney disease and medicines that make your body hold on to potassium.2 UK and European guidelines only call it high from 5.5.2,3
Not urgent if you feel well. Get it rechecked within a few days.2
- 1 Repeat the test within 3 days, and keep your hand relaxed during the draw.1,2
- 2 Don’t stop a blood pressure or heart medicine on your own. Ask the clinician who prescribed it.2,5
- 3 Stop over-the-counter potassium supplements and potassium-based salt substitutes until it’s sorted out. Ask before stopping prescribed potassium.2
High: get it rechecked today
This is moderately high.2,3 It may still be a sample problem, but it needs checking quickly, because high potassium can upset your heart rhythm.1,2
Get it rechecked today. If you feel unwell or weak, or have palpitations, go to an emergency department now.1,2
- 1 Call the clinician who looks after your medicines today.
- 2 Stop over-the-counter potassium supplements and potassium-based salt substitutes.2
Very high: go to an emergency department
At 6.5 or higher, high potassium is severe and can cause dangerous heart rhythms. Guidelines advise immediate hospital assessment, even though a sample problem is still possible.2,5
Go to an emergency department now.
- 1 Take this result and a list of your medicines with you.
What is potassium?
Think of potassium as the charge in your cells’ batteries. Almost all of it sits inside your cells. The small amount in your blood sets how easily nerves and muscles fire, including your heart, so small changes matter.
Your kidneys keep blood potassium in a narrow range, mostly by adjusting how much they pass in your urine.1 If your kidneys work well, what you eat barely moves it.9
Why is my potassium high?
First, rule out the sample. Potassium leaks out of blood cells when you clench your fist during the draw, the draw is difficult or the sample sits too long before it reaches the lab.1,2,4 That’s why guidelines repeat an unexpected high result before treating it.2
If it’s real, the usual causes are:1,2,5
- Kidney disease
- Blood pressure and heart medicines that make your body hold on to potassium: ACE inhibitors, ARBs and the MRAs spironolactone, eplerenone and finerenone
- Potassium-sparing water pills, such as amiloride
- Trimethoprim, an antibiotic, and painkillers such as ibuprofen
- Potassium supplements and potassium-based salt substitutes, on top of these medicines
A newer class of blood pressure drug raises potassium too. Baxdrostat, approved by the FDA in 2026, lowers the hormone aldosterone. In its trials, high potassium was reported in 10.2% of people on the usual 2 mg dose, against 2.5% on a placebo.8
Why is my potassium low?
- Water pills, such as hydrochlorothiazide and chlorthalidone1
- Losing fluid through vomiting or diarrhea, or from bowel preparation for a colonoscopy1
- Too much aldosterone, a hormone that also raises blood pressure (primary aldosteronism)1,6
About 20% to 35% of people with high blood pressure and low potassium have primary aldosteronism. But a normal potassium doesn’t rule it out: US guidelines now advise screening everyone with hard-to-treat high blood pressure, whatever their potassium.6
How to lower high potassium
- Reviewing your medicines and supplements
Painkillers such as ibuprofen, the antibiotic trimethoprim, potassium supplements and salt substitutes can all push potassium up. Stopping these comes first.2,5
- How much it helps
- Some
- How sure we are
- Fairly sure
- Potassium binders
Medicines such as patiromer and sodium zirconium cyclosilicate carry potassium out through your gut, so you can stay on heart and kidney medicines.2,5
- How much it helps
- A lot
- How sure we are
- Very sure
- A water pill
Some diuretics make your kidneys pass more potassium, and clinicians use them for this.2,5
- How much it helps
- Some
- How sure we are
- Fairly sure
- Fewer potassium-rich processed foods
Only if you have moderate or advanced kidney disease and keep running high. Additives and salt substitutes carry potassium your body absorbs easily.5
- How much it helps
- A little
- How sure we are
- Early evidence
Kidney guidelines treat stopping an ACE inhibitor, ARB or similar medicine as a last resort, because these medicines protect your heart and kidneys.5 UK guidance advises pausing them at 6.0 or higher unless a potassium binder is an option. That’s a decision for your clinician.2
Are potassium salt substitutes safe?
For most people, yes. US blood pressure guidelines say salt substitutes made with potassium can help lower blood pressure.6 In a trial of 20,995 people in rural China with high blood pressure or a past stroke, a substitute that was 25% potassium cut strokes by 14%. Serious events blamed on high potassium didn’t rise, though blood potassium wasn’t routinely measured.7
But that trial left out people with serious kidney disease or on potassium-sparing pills or potassium supplements.7 If you have kidney disease or take a medicine that raises potassium, check with a clinician before you switch.6
Who should get a potassium test?
It’s part of the standard metabolic panel. It’s most worth checking if:
- You take an ACE inhibitor or ARB. Guidelines advise a check 1 to 2 weeks after starting it or raising the dose.2
- You take spironolactone, eplerenone or finerenone, which need regular checks.2,5
- You take a water pill.1
- You have kidney disease, or diabetes with kidney damage.5
- You’ve had vomiting or diarrhea for days.1
How to get a potassium test, and what it costs
It comes from the comprehensive metabolic panel, which costs $4.00 through Picardo.
Comprehensive metabolic panel
The test this number comes from.
- Results in 2 to 3 days, in the app
- Physician follow-up if you want one
- Free Labcorp draw, or $75 at home
- No other fees. HSA and FSA eligible.
It’s also part of the Base Core Annual – Men, Base Core Annual – Women, Heart Health, Brain Health Screening, Pregnancy, Postpartum, Fertility, Thyroid & Autoimmunity and Celiac / GI panels, if you’d rather test more at once.
Already have a result? Ask Picardo about itQuestions people ask
Can a blood test show high potassium by mistake?
Yes, often. Clenching your fist, a difficult draw, shaking the tube or a long wait before the sample reaches the lab can all push the number up. Very high platelet or white cell counts can too.1,2,4 That’s why an unexpected high result is repeated before it’s treated.2
Do bananas raise your potassium level?
Not if your kidneys work well. They keep blood potassium steady, so food barely moves it.9 With moderate or advanced kidney disease and a history of high potassium, food choices matter more, and a kidney dietitian can help.5
How much potassium should I eat?
For blood pressure, US guidelines suggest 3,500 to 5,000 mg a day, ideally from food such as fruit, vegetables and beans. If you have kidney disease or take a medicine that raises potassium, your clinician may want to check your level first.6
Should I stop my blood pressure medicine if my potassium is high?
Not on your own. ACE inhibitors, ARBs and similar medicines protect your heart and kidneys, so kidney guidelines try other steps first.5 UK guidance does advise pausing them at 6.0 or higher, or during an acute illness. That’s your clinician’s call.2
Are potassium salt substitutes safe?
For most people, yes. In a large trial in rural China of people with high blood pressure or a past stroke, they cut strokes and deaths, and serious events blamed on high potassium didn’t rise, though blood potassium wasn’t routinely measured.7 The trial left out people with serious kidney disease or on potassium-sparing pills or potassium supplements, so check with a clinician first if any of those applies to you.6,7
Often checked alongside
Test details
- Labcorp test
- Metabolic Panel (14), Comprehensive, 322000
- LOINC
- 2823-3
- Sample
- Blood (serum)
- Fasting
- Not needed for potassium itself. The metabolic panel it comes on asks for 12 hours, for its glucose result.
- Typical lab range
- 3.5 to 5.2 mmol/L for adults4
- Units
- mmol/L, the same as mEq/L. Serum reads 0.1 to 0.7 higher than plasma.1
Sources
- 1 Clase CM, Carrero JJ, Ellison DH, et al. Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney Int. 2020;97(1):42–61. doi.org/10.1016/j.kint.2019.09.018
- 2 Alfonzo A, Harrison A, Baines R, et al. Clinical practice guidelines: treatment of acute hyperkalaemia in adults. UK Kidney Association; updated July 2026. www.ukkidney.org/sites/default/files/documents/FINAL%20VERSION%20-%20UKKA%20CLINICAL%20PRACTICE%20GUIDELINE%20-%20MANAGEMENT%20OF%20HYPERKALAEMIA%20IN%20ADULTS%20-%20UPDATED%20JULY%202026_0.pdf
- 3 Lott C, Karageorgos V, Abelairas-Gomez C, et al. European Resuscitation Council Guidelines 2025 special circumstances in resuscitation. Resuscitation. 2025;215(Suppl 1):110753. doi.org/10.1016/j.resuscitation.2025.110753
- 4 Labcorp. Potassium, test 001180. Labcorp test menu. Accessed October 28, 2026. www.labcorp.com/tests/001180/potassium
- 5 Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int. 2024;105(4S):S117–S314. doi.org/10.1016/j.kint.2023.10.018
- 6 Jones DW, Ferdinand KC, Taler SJ, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM guideline for the prevention, detection, evaluation and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Hypertension. 2025;82(10):e212–e316. doi.org/10.1161/HYP.0000000000000249
- 7 Neal B, Wu Y, Feng X, et al. Effect of salt substitution on cardiovascular events and death. N Engl J Med. 2021;385(12):1067–1077. doi.org/10.1056/NEJMoa2105675
- 8 AstraZeneca. BAXFENDY (baxdrostat) tablets: prescribing information. Initial US approval 2026. Revised May 2026. www.accessdata.fda.gov/drugsatfda_docs/label/2026/219878Orig1s000lbl.pdf
- 9 National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium. Washington, DC: National Academies Press; 2019. doi.org/10.17226/25353
Updated 28 Oct 2026.
This is general health information, not medical advice: talk to your clinician about your results and before changing any treatment.