Potassium is a powerhouse mineral and electrolyte that is essential for every cell in your body. While sodium primarily manages fluid outside your cells, potassium lives mostly inside your cells.
Its most critical job? Ensuring your heart beats steadily and your muscles contract smoothly.
Because potassium controls the electrical signals in your heart, your body regulates it with extreme precision. Even a small shift outside the normal range can be significant.
A normal blood potassium level is between 3.5 and 5.3 mmol/L.
Note: “Normal” ranges can vary slightly between different laboratories. Always consult the specific reference range listed on your blood test results.
When potassium levels drift, they are categorized into two main conditions. Because potassium is so vital for electrical conductivity, both ends of the spectrum can affect heart rhythms.
| Condition | Level | Definition |
| Hypokalaemia | Below 3.5 mmol/L | Low blood potassium |
| Hyperkalaemia | Above 5.3 mmol/L | High blood potassium (Potentially life-threatening) |
Why do these levels matter?
Potassium is the primary driver of electrical activity in muscle fibers.
High potassium can “short-circuit” the heart’s electrical system, leading to dangerous arrhythmias or sudden cardiac arrest.
Low potassium can cause muscles to become weak or paralysed and makes the heart “irritable,” leading to palpitations.
Hypokalaemia usually occurs when the body loses too much fluid or when potassium is driven into the cells too quickly.
Digestive Losses: Prolonged vomiting or severe diarrhea can lead to significant potassium loss.
Diuretics: Non-potassium-sparing “water pills” (like Furosemide or Bumetanide) flush potassium out through the urine.
Sweating: Excessive sweating during intense heat or exercise.
Magnesium Deficiency: Low magnesium levels make it very difficult for the kidneys to hold onto potassium.
Treatment depends on the severity of the imbalance and how quickly it developed.
This is usually treated with oral supplements (Sando-K) or by increasing dietary intake (bananas, potatoes, spinach). In severe cases, potassium is replaced slowly via an intravenous (IV) drip.
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