Potassium
Everything you need to know about Potassium levels, including what normal ranges look like and what abnormal results might indicate.
Standard Reference Range
Unit: mmol/LReference ranges may vary slightly between laboratories. Always consult your doctor for interpretation.
What is Potassium?
Potassium is a crucial electrolyte for heart rhythm, muscle function, and nerve signals. It's tightly regulated as abnormal levels can cause life-threatening arrhythmias.
Key Takeaway
Potassium levels outside the normal range can cause fatal heart arrhythmias. Both high and low levels require prompt attention.
Why is this test performed?
Potassium testing helps:
- Monitor kidney disease
- Assess heart rhythm problems
- Monitor diuretic therapy
- Evaluate muscle weakness
- Check acid-base balance
Interpreting Your Results
Low Potassium (Hypokalemia)
＜3.5 mmol/L indicates low potassium:
Mild (3.0-3.5):
- Muscle weakness, cramps
- Fatigue
- Constipation
Moderate (2.5-3.0):
- Heart palpitations
- Muscle pain
- Arrhythmias
Severe (＜2.5):
- Paralysis
- Respiratory failure
- Life-threatening arrhythmias
Common Causes:
- Diuretic medications
- Vomiting or diarrhea
- Laxative abuse
- Low dietary intake
- Hyperaldosteronism
- Renal tubular acidosis
High Potassium (Hyperkalemia)
＞5.0 mmol/L indicates high potassium:
Mild (5.1-6.0):
- Often no symptoms
- Muscle weakness
Moderate (6.1-7.0):
- Muscle weakness
- Tingling/numbness
- Nausea
Severe (＞7.0):
- Cardiac arrest risk
- Paralysis
- Medical emergency
Common Causes:
- Kidney disease (most common)
- ACE inhibitors or ARBs
- Potassium-sparing diuretics
- Addison's disease
- Cell breakdown (hemolysis, tumor lysis)
- Excess supplements
Treatment
For Hypokalemia:
- Oral potassium supplements
- Potassium-rich foods (bananas, potatoes, spinach)
- IV potassium (severe cases)
- Treat underlying cause
For Hyperkalemia:
- Emergency (＞6.5 or ECG changes):
- Calcium gluconate (protect heart)
- Insulin + glucose (shift K into cells)
- Dialysis (if severe kidney disease)
- Non-emergency:
- Stop potassium supplements
- Adjust medications
- Low-potassium diet
- Diuretics
Important Notes
False Results:
- Hemolysis (broken red cells) falsely elevates
- Tight tourniquet or fist clenching raises levels
- Recheck if result doesn't fit clinical picture
ECG Monitoring:
- Required for severe abnormalities
- Hyperkalemia causes peaked T waves, wide QRS
Related Tests
- Aldosterone/Renin: If unexplained abnormality
- Creatinine: Assess kidney function
- Magnesium: Often low with hypokalemia
- Acid-base status: Affects potassium distribution
Decode your Serum Potassium Results
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