What is the Potassium test?

The Potassium blood test measures the level of potassium in the bloodstream, a vital electrolyte required for normal nerve transmission, muscle contraction, and heart rhythm regulation.

Potassium balance is tightly controlled by the kidneys and hormones. Even small changes can affect cardiac function and neuromuscular activity, making accurate measurement clinically important.

This test is commonly performed alongside other electrolytes and kidney function markers to assess fluid and mineral balance.

Why do I need a test for Potassium?

Abnormal potassium levels can cause significant symptoms and, in severe cases, life-threatening complications. Testing helps identify electrolyte imbalance early and supports safe clinical management.

It is particularly important for people with kidney disease, those taking certain medications, or individuals with symptoms affecting muscles or heart rhythm.

You may benefit from this test if you experience:

• Muscle weakness or cramps

• Irregular heartbeat or palpitations

• Fatigue or lethargy

• Tingling or numbness

• Kidney disease

• Use of diuretics or blood pressure medication

• Dehydration or fluid imbalance

• Monitoring of chronic illness

Benefits of the Potassium test

1. Assesses electrolyte balance
   Helps determine whether potassium levels are within a safe range.

2. Supports heart rhythm assessment
   Abnormal levels can affect cardiac electrical activity.

3. Evaluates muscle and nerve function
   Potassium is essential for neuromuscular signalling.

4. Supports kidney function evaluation
   Kidneys play a key role in potassium regulation.

5. Monitors medication effects
   Certain drugs can raise or lower potassium levels.

6. Supports chronic disease management
   Useful in kidney, heart, and endocrine conditions.

7. Identifies dehydration or fluid imbalance
   Potassium levels can shift with fluid loss or excess.

8. Guides further clinical investigation
   Abnormal results may prompt additional testing or review.

Step-by-step – how we offer Potassium testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic

• Attend your appointment

• A qualified clinician or phlebotomist collects your blood sample

• Sample is sent to the laboratory for analysis

At-home or hotel testing (+£60)

• A qualified phlebotomist visits your home or hotel

• Blood sample collected in a comfortable, familiar setting

• No clinic visit or travel required

Both services are available UK-wide.

Your Potassium results explained

Low potassium levels (hypokalaemia)

Low potassium can interfere with muscle and nerve function and may affect heart rhythm. Common causes include vomiting, diarrhoea, diuretic use, or inadequate intake.

Symptoms may include muscle weakness, cramps, fatigue, and irregular heartbeat.

UK reference range:

• Low: <3.5 mmol/L

Normal potassium levels

Normal potassium levels indicate balanced electrolyte regulation and effective kidney function. This supports stable muscle contraction and normal heart rhythm.

Results should be interpreted alongside other electrolytes and clinical context.

UK reference range:

• Normal: 3.5–5.3 mmol/L

High potassium levels (hyperkalaemia)

High potassium levels can be dangerous and may disrupt heart rhythm. Common causes include kidney dysfunction, certain medications, or cellular breakdown.

Symptoms may include weakness, tingling, or cardiac rhythm disturbances.

UK reference range:

• High: >5.3 mmol/L