Kidney / U&E
Urea blood test
A urea blood test measures urea, a waste product made when your body breaks down protein and normally filtered out by your kidneys. It forms part of a kidney function panel (U&Es), but because urea is also affected by how hydrated you are and how much protein you eat, it's interpreted alongside creatinine and eGFR rather than on its own.
- What it measures
- Urea, a waste product filtered by your kidneys
- Sample
- Venous blood sample
- Fasting
- Not required
- Also known as
- blood urea, serum urea
- Included in 57 Health tests
- 8 panels, from £95
Urea reference range
Guide only| Category | Guide range |
|---|---|
| Adults | 2.5–7.8 mmol/L |
Urea is influenced by hydration, diet (protein intake) and the gut as well as kidney function, so it's read together with creatinine and eGFR, the urea and electrolytes (U&E) panel, for a reliable picture of the kidneys.
These are general UK adult guide ranges from public health sources, shown for orientation only. Reference ranges vary by laboratory, assay, age and sex, so your result is always interpreted against the range quoted by the analysing laboratory on your report.
What does a high urea level mean?
A high urea often reflects dehydration or a high-protein intake rather than a kidney problem, but it can indicate reduced kidney function or bleeding in the digestive tract.
Because urea alone is easily swayed by hydration and diet, creatinine and eGFR are used alongside it to judge whether the kidneys themselves are affected.
What does a low urea level mean?
A low urea is usually not a concern.
It can occur with a low-protein diet, overhydration, pregnancy, or with liver conditions (since the liver makes urea), and is interpreted in the context of your other results.
When to consider a urea test
- A general health or kidney function check
- Known high blood pressure or diabetes
- Symptoms of dehydration
- Monitoring the kidneys while on certain medicines
- Following up an abnormal previous result
Frequently asked questions
This page is general information about a blood marker and is not medical advice or a diagnosis. A urea test screens and gives context; results are interpreted by a clinician alongside your symptoms, history and other markers. Always follow the guidance on your own report.