What is the Urea & Electrolytes test?

The Urea & Electrolytes (U&E) test is a blood test that evaluates how well the kidneys are functioning and whether the body’s fluid and electrolyte balance is stable. The kidneys play a key role in filtering waste, regulating blood pressure, and maintaining electrolyte levels.

This test typically measures urea, creatinine, sodium, potassium, chloride, and bicarbonate, and often includes an estimated glomerular filtration rate (eGFR). Together, these markers provide a clear picture of kidney health and internal chemical balance.

It is one of the most commonly requested blood tests in both routine and urgent clinical assessment.

Why do I need a Urea & Electrolytes test?

Electrolyte imbalances and kidney dysfunction can cause a wide range of symptoms and may develop silently. Early testing helps identify problems before complications arise.

You may need this test if you experience:

• Fatigue or weakness
• Dehydration or fluid retention
• Muscle cramps or irregular heartbeat
• Confusion or dizziness
• Reduced urine output
• High blood pressure
• Vomiting or diarrhoea
• Use of medications affecting kidneys or electrolytes
• Monitoring known kidney disease

The test helps determine whether symptoms are related to kidney function, hydration, or electrolyte imbalance.

Benefits of the test

1. Assesses kidney function
   Evaluates waste filtration and renal performance.
2. Detects dehydration or fluid overload
   Sodium and urea reflect fluid balance.
3. Identifies electrolyte imbalance
   Sodium and potassium are critical for nerve and muscle function.
4. Supports medication monitoring
   Important when using diuretics or blood pressure treatments.
5. Useful in acute and chronic conditions
   Widely used in routine and urgent care.
6. Monitors kidney disease progression
   Helps track changes over time.
7. Simple blood-based testing
   Requires only one blood sample.
8. Essential baseline health check
   Often included in general health panels.

Step-by-step: How we offer testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician draws a blood sample
• Sample is sent to the laboratory
• Results are issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Book a mobile phlebotomist
• Blood sample taken at your home or hotel
• No need to attend a clinic
• Sample securely transported to the laboratory

Your results explained

Low levels

• Low sodium – may cause confusion, headaches, weakness
• Low potassium – may affect muscle function and heart rhythm
• Low urea – often related to hydration or diet

Typical UK reference examples (may vary):

• Sodium: <135 mmol/L
• Potassium: <3.5 mmol/L

Normal levels

• Urea, electrolytes, creatinine, and eGFR within reference range
• Suggests normal kidney function and fluid balance

High levels

• High urea or creatinine – reduced kidney filtration or dehydration
• High potassium – may affect heart rhythm
• High sodium – often linked to dehydration

Typical UK reference examples:

• Sodium: >145 mmol/L
• Potassium: >5.0 mmol/L
• eGFR: <60 mL/min/1.73m² (reduced kidney function)

Results should always be interpreted together and in clinical context.