Potassium
Potassium is the main electrolyte inside cells. Tight regulation is critical for nerve transmission, muscle contraction (especially the heart), and acid-base balance. Both high (hyperkalaemia) and low (hypokalaemia) potassium can cause life-threatening arrhythmias.
Normal Range
3.5–5.0 mmol/L
Reference ranges may vary slightly between laboratories. Always interpret your result in context with your doctor.
Why is K+ measured?
Potassium is part of every basic metabolic panel. It is tested in any acute illness, monitored in patients on diuretics, ACE inhibitors, ARBs, kidney disease, and diabetes (DKA).
High K+ means…
High potassium (>5.0) is dangerous. Above 6.0 may cause cardiac arrhythmias; above 6.5 is a medical emergency. Causes include kidney disease, certain medications (ACE inhibitors, spironolactone, NSAIDs), and acidosis.
Low K+ means…
Low potassium (<3.5) causes muscle weakness, cramps, and arrhythmias. Common causes include diuretics, vomiting, diarrhoea, and insufficient dietary potassium.
Symptoms associated with abnormal K+
When K+ is high:
- Muscle weakness
- Heart palpitations or irregular rhythm
- Numbness or tingling
- Nausea
- Cardiac arrest in severe cases
When K+ is low:
- Muscle cramps and weakness
- Fatigue
- Heart palpitations
- Constipation
- Tingling, numbness
How to improve your K+
- Do not take potassium supplements without medical advice — kidney function and other medications matter.
- On ACE inhibitors / ARBs / spironolactone, periodic monitoring is essential.
- Magnesium deficiency causes refractory hypokalaemia — correct magnesium too if low.
Frequently asked questions about K+
What potassium level is an emergency?
Potassium above 6.5 mmol/L or below 2.5 mmol/L can cause life-threatening arrhythmias and warrants immediate treatment, particularly if accompanied by ECG changes.
Medical Sources
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider about your individual results.