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Kidney Function Test
Urea, creatinine and the calculated eGFR together, the standard three-result check of kidney function.
- Doctor-reviewed results
- Laboratory analysis
- 1 to 2 working days from lab receipt
- No fasting required
What’s included
3 markers measured
Urea
Urea is checked together with sodium, potassium and creatinine to assess how well the kidneys are working and the body's fluid balance.
Creatinine
A waste product measured in the blood as the main test for kidney disease. Combined with age and sex, it is used to work out eGFR, an estimate of how much the kidneys can filter each minute. A lower eGFR can point to chronic kidney disease.
eGFR
eGFR (estimated glomerular filtration rate) is an estimate of how well your kidneys filter waste from the blood. It is calculated from the level of creatinine, a waste product, in your blood, together with your age and sex. A lower rate can be a sign of chronic kidney disease.
Overview
These are the three numbers a GP looks at when the question is how the kidneys are filtering: urea, creatinine and the eGFR calculated from creatinine. It is the sensible baseline to have on record if you take blood pressure tablets, regular anti-inflammatories or have diabetes.
These are the three numbers a GP looks at when the question is how the kidneys are filtering. Creatinine and the eGFR calculated from it carry most of the meaning, and urea adds context, particularly about hydration and protein intake. Kidney function is judged on the trend rather than one reading, so if you are following it over time it is worth giving the samples under similar conditions: normally hydrated, and not straight after a hard training session.
Who this is for and who it isn’t
Who it’s for
- Adults aged 18 and over
- Anyone on blood pressure tablets, diuretics or regular anti-inflammatories
- People with diabetes or kidney disease in the family
Who it isn’t for
- Kidney function is judged on trends, not on one set of numbers, and all three results are affected by hydration, and creatinine and the eGFR are also affected by muscle mass and a recent hard training session. This also does not include a urine test, and protein in the urine is one of the earliest markers of kidney damage, so a full assessment includes one. Creatine supplements raise creatinine directly and lower the calculated eGFR without the kidneys changing at all.
- Anyone with a new, severe or worsening symptom: contact your GP or call NHS 111. A test you buy today is not a substitute for being examined.
Common reasons people choose this test
- Taking blood pressure tablets, diuretics or regular anti-inflammatories
- Diabetes or high blood pressure
- Kidney disease in a close relative
- Wanting a baseline before starting a long-term medicine
- Following a previously borderline eGFR
These are reasons people choose to test, not signs that something is wrong. A result is one part of a picture your doctor puts together with your history and an examination.
What your result looks like
Every result is shown with the unit and the reference range exactly as the laboratory reported it, with the doctor’s note underneath.
- Urea▲ High
- Result
- 8.4 mmol/L
- Range
- 2.5–7.8
- CreatinineIn range
- Result
- 78 µmol/L
- Range
- 45–84 / 59–104
- eGFRIn range
- Result
- >90 mL/min/1.73m²
- Range
- >60
| Marker | Result | Units | Range | Flag |
|---|---|---|---|---|
| Urea | 8.4 | mmol/L | 2.5–7.8 | ▲ High |
| Creatinine | 78 | µmol/L | 45–84 / 59–104 | In range |
| eGFR | >90 | mL/min/1.73m² | >60 | In range |
Doctor’s note (example)
Urea is a little raised, most often from not drinking enough before the sample or a high-protein diet. With a normal creatinine and eGFR, kidney function looks normal on these numbers.
Ranges shown as women / men. Values above are examples. Your report shows your own results with the laboratory’s units and reference range for your age and sex, reviewed, signed and released by a GMC-registered doctor.
How it works
- Your kit arrivesPosted to your door, with instructions and what you need to send your sample back.
- You take your sampleFinger-prick sample at home, or a clinic blood draw, your choice
- The laboratory analyses itYour sample is processed for the measurements included in this test. Lab processing typically takes 1 to 2 working days from receipt of your sample.
- A doctor reviews and releases itA GMC-registered doctor reads every result and signs the report before it reaches you.
- Sample
- Home finger-prick kit
- Preparation
- No fasting required
- Who it's for
- Any sex · ages 18+
How to prepare
What we can and can’t tell you
The reference range beside each result is the laboratory’s own. A result in range is not a clean bill of health and a result outside it is not a diagnosis. Most ranges cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one range. No test result replaces an examination or your own doctor’s judgement, and none of these panels is a cancer screening programme.
Read the full note
The reference range printed beside each of your results is the laboratory's own, and it is the range that applies to your result. We do not apply a second range of our own, and we do not tell you that a result the laboratory reported as normal is nonetheless too low or too high. If you see a claim elsewhere that your result ought to sit inside a narrower band than the one the laboratory printed, treat it with caution and ask your doctor.
Some assays cannot give an exact figure above or below a certain point, and those results are reported the way the laboratory sends them, for example as a value greater than a stated number. A result in range is not a clean bill of health, and a result outside a range is not a diagnosis: most reference ranges are set to cover about 95% of healthy people, so some healthy people fall just outside them. No blood test replaces an examination, a scan or your own doctor's judgement, and none of these panels is a screening programme for cancer.
If you have a symptom that is new, severe, or getting worse, contact your GP or NHS 111 rather than waiting for a test result. In an emergency call 999.
Frequently asked questions
How should I prepare?
Do not eat any meat in the 12 hours before your sample, drink normally, avoid a hard training session on the day, and if you take creatine, tell us. No other fasting is needed.
Is eGFR a measurement or a calculation?
A calculation, from your creatinine together with your age and sex. It estimates filtration rather than measuring it, which is why the trend matters more than a single figure.
What if my eGFR is just under 60?
On one reading that does not mean kidney disease. eGFR drifts down with age, and muscle mass and hydration both affect it. UK guidance repeats a first result below 60 within two weeks, checks the urine for protein, and only considers kidney disease based on eGFR alone if the result stays low for at least three months. The doctor's note explains this.
Should I add a urine test?
If kidney health is the real question, yes. Protein in the urine adds information that blood tests cannot give, and a urine albumin to creatinine ratio (ACR) is the test UK kidney guidance uses for it. Your GP can arrange one.
How long do results take?
The laboratory typically takes 1 to 2 working days from receiving your sample. This does not include kit delivery, sample collection or return postage. A doctor reviews your results before they are released.
Can I choose a home kit or a clinic?
Both, it is your choice at checkout. Either collect a finger-prick sample at home with the posted kit and send it back as the instructions explain, or book a clinic appointment and have a trained clinician take the sample for you.
Is a doctor involved?
Yes. Every result is reviewed by a GMC-registered doctor who signs it off and explains what it means and what to do next.
Is it confidential?
Your results are available through your secure patient portal. Our privacy policy explains how your information is handled and when it may be shared to provide your care.
What happens to my sample and results?
Your sample is analysed at a UKAS-accredited laboratory (ISO 15189). A GMC-registered doctor then reads every result and signs the report before it is released, so nothing reaches you unreviewed. There is no option to receive results without a doctor reading them first. The report arrives in your secure portal in plain English: each result with its unit and the laboratory's own reference range, and the doctor's note on what the set means read together. If a result sits outside its range the report says so and explains what usually happens next, which is most often a conversation with your own GP, who can act on it alongside your history and examination. Most reference ranges are set to cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one of them. On a report with many results it is common for one to sit just outside its range, and a single number on its own rarely tells the whole story. If a result needs urgent attention, the reviewing doctor is alerted straight away and we contact you by phone the same working day rather than leaving it in the portal for you to find. If a specific result needs rechecking, the reviewing doctor says so in your report.
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