Last Updated on May 17, 2025 by Analgesia team
U & E Medical Abbreviation
A urea and electrolytes (U&E) blood test, also known as a kidney function test, measures the levels of various substances in your blood to assess your kidney function and fluid and electrolyte balance:
- Electrolytes: Sodium, potassium, chloride, and bicarbonate, which help maintain fluid balance and plasma volume. Abnormal levels can cause abnormal heart rhythms.
- Urea: A protein that is normally broken down by the kidneys. High levels of urea in the blood could indicate kidney problems.
- Other substances: Phosphorus, calcium, albumin, and creatinine.
When is U&E test performed?
- As part of a routine check-up
- To monitor conditions like diabetes or high blood pressure
- To assess kidney function before starting certain medications
- To check for acute kidney injury (AKI)
Blood test results can take around 7 working days to come back, but specialist tests may take longer. You can usually access your results online if you’re registered to use your local practice’s online services. If your doctor wants to see you about your results, they’ll offer you an appointment.
Normal ranges for U and E test results
6 – 7.1mmol/L (SI units) or 10 – 20mg/dL in adults, but slightly higher for older people. 3 – 12mg/dL in newborns. 5 – 18mg/dL in children and infants.
Abnormal U & E result
Abnormal urea and electrolytes (U&E) test results can indicate kidney problems, heart arrhythmias, or other health issues.
What can cause abnormal U&E results?
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- Kidney disease
- Dehydration or overhydration
- Illnesses that cause fluid loss, like vomiting, diarrhoea, or sweating
- Intestinal or digestive issues
- Hormone imbalance
- Medications like antibiotics, diuretics, and some heart and cancer medications
What Does U & E Check For?
A&E blood tests can check for a range of conditions, including HIV, hepatitis B and C, electrolyte imbalances, and kidney dysfunction.
HIV, hepatitis B, and C
- These tests are routinely performed on patients aged 16 and over who have a blood test in an A&E department in the UK.
- The tests are free and confidential.
- Early diagnosis of these conditions is important as treatment is life-saving.
Electrolyte imbalances
- These tests measure the levels of electrolytes in the blood, such as sodium, potassium, and chloride.
- Electrolyte imbalances can cause a range of symptoms, from mild to severe.
- Abnormal levels of electrolytes can also cause abnormal heart rhythms.
Kidney dysfunction
- These tests measure the levels of blood urea nitrogen (BUN) and creatinine in the blood.
- Kidney dysfunction can manifest with a range of symptoms, from mild to severe.
Other conditions
- U & E blood tests can also check for cholesterol levels, blood gas balance, and complete blood count (CBC).
What other kidney function tests are there?
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Creatinine testsMeasure the level of creatinine in your blood, which is filtered out by the kidneys. Higher levels of creatinine indicate kidney dysfunction.
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Estimated Glomerular Filtration Rate (eGFR)A mathematical calculation that estimates kidney function based on serum creatinine levels, age, sex, and race.