Kidney and organ health
Urea and Electrolytes (U&E): What the Test Measures
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed July 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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U&E stands for urea and electrolytes. It is a common blood test that checks how well your kidneys are working and whether your body salts are balanced. It measures sodium, potassium, urea and creatinine, and it is used to spot dehydration, kidney problems and the effect of some medicines.
Find the test that fits your symptoms →As of July 2026.If you have seen “U&E” on a blood form or a set of results, this guide explains what it means. It sticks to NHS wording and UK reference ranges.
U&E is one of the most ordered blood tests in the country. Your GP ticks the box, the lab runs four or five numbers, and you get a result you may not recognise. So what is actually being measured, and what do the numbers tell you?
1. What does U&E stand for?
U&E stands for urea and electrolytes. It is a routine panel of blood tests that checks two things at once. First, how well your kidneys are filtering waste. Second, whether the salts that keep your body running are in balance.
Electrolytes are the salts and minerals in your blood. The NHS defines them simply.
“Electrolytes are salts and minerals, such as sodium, potassium, chloride and bicarbonate, which are found in the blood.”
— NHS, Electrolyte test
You may also see the test called U&Es, a renal profile, or urea and electrolytes. They all mean the same panel. It is one of the checks explained in our full kidney function test guide.
2. What does the U&E test measure?
A standard U&E reports four core markers. Many labs add a calculated eGFR too. Here is what each one means, with the usual UK ranges. Ranges vary a little between labs, so read yours against the range printed on your own report.
- Sodium. The main salt in your blood. It controls fluid balance and helps nerves and muscles work. Typical NHS range: 133 to 146 mmol/L.
- Potassium. Vital for muscle and heart rhythm. Both very high and very low levels matter. Typical NHS range: 3.5 to 5.3 mmol/L.
- Urea. A waste product made when your liver breaks down protein. Your kidneys clear it. It is swayed by hydration and diet. Typical NHS range: 2.5 to 7.8 mmol/L.
- Creatinine.A waste product from normal muscle use, cleared by the kidneys. It is the steadier kidney marker. Typical NHS range: 59 to 104 μmol/L for men, 45 to 84 for women.
- eGFR. Estimated glomerular filtration rate. Not measured directly, but calculated from your creatinine, age and sex. It estimates how fast your kidneys filter. 90 or above is normal.
For a full walk-through of each result, including what high and low numbers point to, see our creatinine blood test guide and the deeper kidney function test guide.
3. Why does my GP order a U&E?
A U&E is a broad check, not a test for one disease. Your GP may add it to a general blood panel, or order it for a specific reason. Common ones include:
- Checking kidney health. Especially if you have diabetes or high blood pressure, which strain the kidneys over time.
- Before or during medication. The NHS notes that your levels may be checked if you take drugs such as diuretics or ACE inhibitors for blood pressure, because they change body salts.
- Investigating symptoms.Tiredness, feeling unwell, swelling or dehydration can all prompt a U&E.
- A routine check. It is a standard part of many general health screens.
The reason kidney checks matter is that early problems are silent. You can lose a lot of function before you feel anything.
“There are usually no symptoms of kidney disease in the early stages.”
— NHS, Chronic kidney disease
That is exactly why a simple number, tracked over time, is useful. It turns a silent trend into something you can see. If a result looks off, our guide to reading blood test results explains the next steps.
4. How to check your kidney markers at home
A hospital U&E includes sodium and potassium, which shift quickly and are usually monitored by your GP alongside your medicines. A home finger-prick test focuses on the steadier kidney-filtration markers you can usefully track over months.
Helvy’s Thyroid & Vital Organs panel (£159) measures urea, creatinine and eGFR, the three markers that show how well your kidneys filter. It reads them alongside your thyroid and liver markers, so you see your organ health in one picture. The General Energy & Wellness panel (£149) also includes urea and creatinine.
To find the panel that fits what you want to check, the build-my-test tool matches you to the right markers. All are home finger-prick tests, with results in about five working days from UKAS-accredited UK laboratories. Sodium and potassium are best checked by your GP if you take medicines that affect them.
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Understand your kidney numbers
Helvy’s home blood tests read urea, creatinine and eGFR with clear context, so you can see how your kidneys are filtering and track it over time. Results in about 5 working days from UKAS-accredited UK laboratories.
Frequently asked questions
What does U&E stand for?
U&E stands for urea and electrolytes. It is a routine blood test that checks kidney function and the balance of body salts. It usually measures sodium, potassium, urea and creatinine, and often a calculated eGFR. This is general information, not medical advice.
Do I need to fast for a U&E blood test?
Usually no. A U&E does not normally need fasting. If your GP has combined it with other tests, such as glucose or a lipid panel, they may ask you to fast for those. Follow the instructions on your appointment letter.
What is a normal U&E result?
As a rough UK guide, sodium sits around 133 to 146 mmol/L, potassium 3.5 to 5.3 mmol/L, and urea 2.5 to 7.8 mmol/L. eGFR of 90 or above is normal. Ranges vary by lab, so read yours against the range printed on your own report.
Can I get a U&E test at home?
You can check the kidney-filtration markers at home. Helvy’s finger-prick panels measure urea, creatinine and eGFR. Sodium and potassium shift quickly and are best checked by your GP, especially if you take medicines that affect them. If a result is abnormal, speak to a qualified clinician.
Related guides
Kidney Function Test UK
The full results guide: creatinine, eGFR, urea and CKD stages.
Creatinine Blood Test UK
What a high creatinine really means, and when it matters.
Liver Function Test UK
What LFTs measure and how to read the results.
Blood Test Reference Ranges
Normal vs optimal ranges across the common UK markers.
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