What are normal potassium levels?

What are potassium levels and what is normal?

Blood potassium is a lab concentration, not a diet target

Potassium is an essential mineral and electrolyte, written as K, and most of it sits inside cells rather than in the bloodstream. The NIH Office of Dietary Supplements potassium fact sheet says blood potassium measures the concentration in serum or plasma, so it reflects only the small fraction outside cells. The same source links potassium with the electrical gradient needed for nerve impulses, muscle contraction, and kidney function, and with blood-pressure regulation.

That is why blood potassium and dietary potassium are different measures. Blood results are reported in mmol/L, while intake is usually discussed in mg/day. A lab value tells you the concentration in a blood sample; an intake target tells you how much potassium is recommended in food. NIH consumer fact sheet EFSA dietary reference values for potassium

Blood potassium is measured in mmol/L; dietary potassium is counted in mg/day.

What range is normal in adults?

For healthy adults, the NIH ODS fact sheet gives an approximate serum or plasma reference range of 3.6 to 5.0 mmol/L. UK guidance in the supplied material defines hyperkalaemia as serum potassium above 5.5 mmol/L, which is one reason lab reports should always be read against the laboratory’s own reference interval and the clinical context. NIH ODS potassium fact sheet NNUH hyperkalaemia guideline

How the sample is handled matters

Both serum and plasma are used, and collection quality can change the result. NHS Highland guidance lists delayed centrifuging, premature centrifuging, EDTA contamination, refrigeration before spinning, haemolysis during venepuncture, and excess cuff time as causes of a false rise. The NNUH guideline also notes artefactual increases caused by potassium released from cells during or after collection. NHS Highland hyperkalaemia guidance NNUH hyperkalaemia guideline

Intake targets are separate from blood targets

To avoid confusion, the dietary adequate intake figures in the supplied material are 3,400 mg/day for adult men and 2,600 mg/day for adult women from NIH, and 3,500 mg/day for adults from EFSA; EFSA lists 4,000 mg/day for lactating women. These are food-intake targets, not blood-level targets. NIH consumer fact sheet EFSA dietary reference values for potassium

What does a low potassium level mean?

Low potassium is called hypokalemia. In healthy adults, the NIH Office of Dietary Supplements gives a reference range of about 3.6 to 5.0 mmol/L, so results below that lower edge are considered low. The same fact sheet describes potassium as mostly an intracellular mineral, which is one reason a serum test does not always reflect total body stores exactly.

How low is mild versus serious?

One practical clue is that the symptoms can be nonspecific at first. The NIH fact sheet lists constipation, fatigue, muscle weakness, and malaise for milder cases, then muscle paralysis, respiratory compromise, glucose intolerance, metabolic encephalopathy in people with kidney disease, and dangerous cardiac arrhythmias when potassium drops further. Hospitalized adults are a higher-risk group: the NIH fact sheet says hypokalemia occurs in up to 21% of hospitalized adults, mostly because of medications such as diuretics.

What usually causes it?

The most common causes in the evidence are gastrointestinal losses such as diarrhea and vomiting, plus medication-related losses and low magnesium. The NIH fact sheet also notes that magnesium deficiency often accompanies or worsens hypokalemia, because it increases urinary potassium excretion and lowers intracellular potassium. Less common causes include pica, heavy sweating, and dialysis.

Low intake can contribute, but a diet that looks normal does not rule hypokalemia out. That is because the problem is often loss from the gut or the kidneys, or a low magnesium state, rather than simply not eating enough potassium.

Clues doctors use to find the cause

• Recent vomiting or diarrhea
• New use of a diuretic medicine
• Signs of low magnesium or a history suggesting it
• Timing that fits a recent illness or a medication change

The key question is not just “is potassium low?” but “why did it fall?”

What causes high potassium levels?

High potassium in the blood is called hyperkalemia. In adults, it is usually defined as a serum potassium above about 5.0 mmol/L, or above 5 mEq/L, but the exact cut-off varies by laboratory and guideline (FDA spironolactone label; FDA label; NIH ODS potassium fact sheet). It may be present with no symptoms at first, which is why an unexpected result should not be assumed to be real without checking it again.

When potassium is truly high

The NHS Highland guideline lists acute kidney injury, chronic kidney disease, interstitial nephritis, tubular disease, and lack of aldosterone, including hyporeninaemic hypo-aldosteronism in diabetics and older adults, Addison’s disease, and congenital adrenal hyperplasia (Right Decisions hyperkalaemia guideline). It also lists drugs that raise potassium, including ACE inhibitors, ARBs, NSAIDs, aldosterone antagonists such as spironolactone or eplerenone, and trimethoprim or co-trimoxazole (Right Decisions hyperkalaemia guideline).

Other common triggers and false alarms

The same guideline lists advanced chronic cardiac failure, acidosis, diabetic ketoacidosis, and cell tissue breakdown such as rhabdomyolysis, haemolysis, tumour lysis, or transfusion as additional causes (Right Decisions hyperkalaemia guideline; NNUH hyperkalaemia guideline). Hyperkalemia can also be a false result. The guideline calls pseudohyperkalemia a common cause of an isolated unexpected rise, especially when there are no ECG changes, symptoms, or kidney disease; haemolysis during venepuncture, excess cuff time, delayed centrifuging, EDTA contamination, refrigeration before spinning, high platelets, and high white cells are all listed as factitious causes (Right Decisions hyperkalaemia guideline).

One high potassium result is a signal to verify, review medicines, and look for a kidney, acid-base, or sample problem before assuming true hyperkalemia.

How it is usually diagnosed

The guideline also advises urgent repeat testing in secondary care when K is 6.0 mmol/L or higher, and emergency referral at higher levels or when ECG changes are present (Right Decisions hyperkalaemia guideline).

When symptoms do occur, the sources describe lethargy, nausea, muscle weakness, paraesthesia, palpitations, and ECG changes, with severe cases linked to dangerous arrhythmias (NIH ODS potassium fact sheet; NNUH hyperkalaemia guideline).

Why are high potassium levels more common in older adults?

Kidney reserve falls, so potassium is cleared less efficiently

Age-related loss of kidney reserve is a central reason potassium rises in later life. The SPRINT manual lists “deterioration of GFR” and “isolated hypoaldosteronism particularly in the elderly” as major causes of hyperkalaemia, and the NHS Highland guideline names chronic kidney disease, acute kidney injury, interstitial nephritis or tubular disease, and lack of aldosterone, including hyporeninaemic hypo-aldosteronism in diabetics and the elderly. SPRINT Manual of Procedures Right Decisions guideline

The Leicester formulary makes the age point directly: “the elderly may insidiously develop hyperkalaemia due to deterioration in renal function.” It also warns that potassium-sparing diuretics are contraindicated in renal failure and need close monitoring when used with other agents that raise serum potassium. Leicester formulary

Medicines matter because the margin is smaller

Guidelines consistently list the same high-risk drug groups in older adults: ACE inhibitors and ARBs, spironolactone and eplerenone, NSAIDs, and trimethoprim/co-trimoxazole. The SPRINT manual also names beta blockers, cyclosporine, tacrolimus, direct renin inhibitors, potassium supplements, and potassium-containing salt substitutes as associated with hyperkalaemia. Right Decisions guideline SPRINT Manual of Procedures

The practical problem is combination exposure: if kidney excretion is already reduced, a potassium-raising medicine or salt substitute can matter more than it would in a younger person with normal renal reserve. The NIH Office of Dietary Supplements notes that dietary potassium from foods rarely causes harm in healthy people, but high supplemental doses or potassium-containing salt substitutes can trigger acute hyperkalaemia if excretion capacity is exceeded. Potassium fact sheet

Comorbidity and acute illness can tip a stable level upward

Heart failure and advanced chronic cardiac failure are named in the NHS Highland guidance as settings that can accompany hyperkalaemia, and the same guideline advises patients on these medicines to follow sick day rules and withhold them during acute illness because of AKI and hyperkalaemia risk. Diabetes is also specifically named in the elderly through hyporeninaemic hypo-aldosteronism. Right Decisions guideline

That is why a “mild” rise in potassium should not be assumed to be dietary alone in an older adult. When the clinical picture does not fit, the guideline says pseudo-hyperkalaemia is common with an isolated rise in potassium, especially if there are no ECG changes, symptoms, or kidney disease, and it recommends checking the laboratory if uncertainty exists. Right Decisions guideline

Can you check potassium levels at home?

The FDA says home-use tests exist for some conditions, but they should not replace periodic visits to your doctor and are best read together with your medical history, a physical exam, and other testing FDA home-use tests guidance.

What a home reading can and cannot tell you

A potassium result can be misleading when the sample is affected by pseudo-hyperkalaemia. The NHS Highland guideline says this is common when potassium is unexpectedly high and there are no ECG changes, no symptoms, or no kidney disease; it also lists problems such as delayed centrifuging, premature centrifuging, EDTA contamination, refrigeration before spinning, haemolysis, and high platelets or white cells Right Decisions: Hyperkalaemia primary care guidance.

The same guideline says symptoms can include lethargy, nausea, muscle weakness, and paraesthesia, and it advises an ECG when potassium is above 6.0 mmol/L Right Decisions: Hyperkalaemia primary care guidance.

When a lab repeat is still needed

The guideline recommends repeat testing within 24 hours for potassium 6.0 to 6.4 mmol/L, urgent referral at 6.5 mmol/L or higher, and urgent review if potassium rises by more than 0.5 mmol/L over 6 to 12 hours Right Decisions: Hyperkalaemia primary care guidance.

If there is any chance of fragile blood cells, such as CLL, thrombocytosis, leucocytosis, or vasculitis, the guideline says to send a whole-blood potassium in a lithium heparin tube and mark it for the on-call consultant biochemist Right Decisions: Hyperkalaemia primary care guidance.

Questions to ask about monitoring

Ask your clinician how often potassium should be rechecked after a medication change, what result should trigger a same-day call, and whether a borderline or unexpected number needs confirmation. The NHS guidance gives practical thresholds for those decisions and makes clear that isolated or unexpected results should be interpreted in context Right Decisions: Hyperkalaemia primary care guidance.

Which foods help lower potassium levels?

The diet strategy changes with the problem: when potassium is high, the aim is usually to reduce intake; when potassium is low, a “low-potassium” list is the wrong tool. The NHS Highland hyperkalaemia guideline says to review medicines and diet, and it flags banana, nuts, dried fruits and avocado as common higher-potassium foods to check first.

Lower-potassium foods to compare

USDA food-composition data gives practical per-serving comparisons for foods that are relatively lower in potassium. These figures help with swaps and portion planning, but they do not replace a full day’s diet review. Source: USDA National Nutrient Database: Potassium.

Preparation and hidden sources

Another easy miss is salt substitutes. The FDA label for spironolactone warns patients to avoid potassium supplements and foods containing high levels of potassium, including salt substitutes. That matters because a low-sodium swap can still add potassium back into the diet.

When generic lists are not enough

People with chronic kidney disease or recurrent hyperkalaemia should get individualized advice rather than relying on generic lists alone. Potassium problems are often multifactorial, so the right food plan needs to fit the full clinical picture, not just one shopping list.

If potassium is high, look for lower-potassium swaps; if potassium is low, do not restrict by default.

Who needs extra caution with potassium?

Potassium is riskier when the body cannot excrete it normally, or when a medicine already pushes levels up. NHS Highland lists chronic kidney disease, acute kidney injury, lack of aldosterone in diabetics and the elderly, Addison’s disease, congenital adrenal hyperplasia, advanced cardiac failure, acidosis, diabetic ketoacidosis, and excess potassium intake as common contributors to hyperkalaemia; the NIH fact sheet also names chronic kidney disease, congestive heart failure, adrenal insufficiency, and liver disease as conditions that raise risk. NHS Highland hyperkalaemia guidance NIH ODS potassium fact sheet

Medicines and products that can raise potassium

The most common drug contributors named in the guidance are ACE inhibitors, ARBs, NSAIDs, aldosterone antagonists such as spironolactone or eplerenone, and trimethoprim or co-trimoxazole. The same NHS page also flags potassium supplements and potassium-containing foods or supplements as possible contributors, while the FDA label for spironolactone warns that risk is increased by impaired renal function, potassium supplementation, potassium-containing salt substitutes, and other drugs that increase potassium. The Leicestershire formulary adds that potassium-sparing diuretics can cause hyperkalaemia in older adults when renal function deteriorates, and that ciclosporin may also increase risk. NHS Highland hyperkalaemia guidance FDA spironolactone label LLR formulary on potassium-sparing diuretics

Do not start potassium supplements or potassium-containing salt substitutes on your own if you already have reduced kidney function or take potassium-raising medicines.

Why self-starting or stopping on your own is risky

A supplement amount that may be unremarkable for one person can accumulate when urinary excretion is reduced. That is why potassium should be treated cautiously in people with kidney disease, heart failure, diabetes, adrenal disease, or in older adults taking potassium-raising medicines. NHS Highland hyperkalaemia guidance

Seek urgent medical help if severe muscle weakness, palpitations, paraesthesia, or other rapidly worsening symptoms appear. NHS Highland says severe hyperkalaemia can cause ECG changes and carries a risk of cardiotoxicity and sudden cardiac death, and the NIH notes that severe cases can progress to muscle weakness, paralysis, and dangerous cardiac arrhythmias. NHS Highland hyperkalaemia guidance NIH ODS potassium fact sheet

How is high potassium treated?

Emergency treatment is based on the ECG and kidney function

It recommends an ECG when K+ is above 6.0 mmol/L, and urgent referral when K+ is ≥6.5 mmol/L, or ≥6.0 mmol/L with stage 1 AKI, or ≥5.5 mmol/L with ECG changes NHS Highland primary care hyperkalaemia guidance. The warning signs listed there include bradycardia, absent P waves, PR prolongation, peaked T waves, widened QRS, VT and VF NHS Highland primary care hyperkalaemia guidance.

Hospital treatment has three jobs: stabilize the heart, shift potassium into cells, and then remove potassium from the body FDA hyperkalemia review. IV calcium is used for cardiac membrane stabilization; insulin with glucose is the fastest shifting therapy described in the evidence here, because its effect begins in 10 to 20 minutes, peaks at 30 to 60 minutes, lasts 4 to 6 hours, and usually lowers serum potassium by 0.5 to 1.2 mmol/L NNUH adult hyperkalaemia guideline. Nebulised beta-agonists are another shifting option: the effect starts at about 30 minutes, peaks at 90 minutes, lasts 2 to 6 hours, and lowers serum potassium by 0.5 to 1.0 mmol/L NNUH adult hyperkalaemia guideline.

Removing potassium from the body

After the immediate danger is controlled, treatment turns to potassium removal and to the trigger behind the rise. The FDA review describes elimination strategies that include cation-exchange resins and dialysis FDA hyperkalemia review. In primary care guidance, the most common action is to withhold the likely offending drug, then review medicines and diet for causes NHS Highland primary care hyperkalaemia guidance. Loop diuretics such as intravenous furosemide may be used in acute care, although the NNUH guideline notes that diuretic therapy can be limited when renal function is impaired NNUH adult hyperkalaemia guideline.

When mild elevations keep coming back

For recurrent mild hyperkalaemia, the outpatient plan in the guidance is repeat blood tests, medicine review, and kidney assessment, with diet review when relevant NHS Highland primary care hyperkalaemia guidance. For mild cases, it also recommends repeat testing within days rather than waiting too long, depending on clinical circumstance NHS Highland primary care hyperkalaemia guidance.

If the ECG is changing, the first job is to protect the heart; then potassium is brought down and the cause is removed.

What potassium products does Tigoo stock?

Snapshot of the range

At Tigoo’s 2026-09-18 catalog snapshot, the potassium range contains 5 products, and the median declared product amount is 99.00 mg. Those are catalog figures, not a medical dose recommendation and not proof that one item is better than another.

How to read a potassium label

When you compare products, read four things in order: the compound form named on the pack, the elemental potassium amount per serving, the serving count, and the product’s intended use. The NIH Office of Dietary Supplements says potassium supplement labeling should state the amount of elemental potassium, not just the weight of the salt compound, on the Supplement Facts panel. NIH ODS potassium fact sheet

A common mistake is to compare only the salt name or only the number of capsules. Two products can look similar and still deliver different amounts of elemental potassium per serving, so the serving panel is the number to check first. The same fact sheet also notes that products above 99 mg elemental potassium are handled differently on labels, which is another reason the amount per serving matters when you are scanning a shelf or product page. NIH ODS potassium fact sheet

Choose by purpose, not by catalog number

If the goal is general supplementation, compare the label details and choose the form and serving size that fit the routine. If the goal is to address a medical potassium abnormality, compare products against clinician advice instead of catalog figures; a declared amount does not show whether a product is appropriate for that situation.

Catalog amounts help you compare labels, but they do not tell you whether a potassium product is the right choice for a medical problem.

For readers who are simply comparing retail options, the practical shortcut is to start with elemental potassium, then check the compound form and serving count before deciding.