Potassium
Potassium is the main electrolyte inside cells; essential for the function of the heart, muscles and nerves. The body maintains it carefully within a narrow range, since both too high and too low disturb the heart rhythm.
| Rating | Range |
|---|---|
| Talk to a doctor | below 3 mmol/L |
| Worth improving | 3 – 3.5 mmol/L |
| Good | 3.5 – 5.1 mmol/L |
| Worth improving | 5.1 – 6 mmol/L |
| Talk to a doctor | 6 – 6.5 mmol/L |
| Talk to a doctor | 6.5 mmol/L and above |
Why it matters
High or low potassium can be important for the heart.
If it’s low
Low potassium (hypokalemia) can cause muscle weakness, cramps and rhythm disturbances. Common with losses (vomiting, diarrhea, diuretics).
If it’s high
High potassium (hyperkalemia) can be dangerous for the heart. Common with reduced kidney function and certain medications; a mild rise is sometimes a sampling artifact (sample hemolysis).
What to do
Potassium is critical — do not correct marked abnormalities yourself with supplements/diet without a doctor. Mild fluctuations often follow the cause (hydration, medications).
Read together with
Sodium · Magnesium · eGFR
Part of the guide: Kidneys & electrolytes →
Articles about this marker
- Blood chemistry tests: normal values for ALT, AST, GGT, CRP, CK, creatinine and glucoseReading your report
- Kidneys: eGFR and creatinine — what they mean and how to protect themMarker explained
- Potassium high or low? What your potassium and sodium results meanMarker explained
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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