eGFR Renal Function Test: How to Understand Your Results in the UK
An eGFR renal function test estimates how efficiently your kidneys are filtering waste from the blood. It is one of the most commonly reported markers in UK blood testing, yet many people receive their eGFR result without a clear sense of what the number actually means or when it may warrant further attention.
If you have recently had a kidney function blood test, your report will almost certainly include an eGFR value. This number is calculated from your creatinine level, age, and sex, and it provides a snapshot of how well your kidneys appear to be filtering at that point in time. Understanding what your eGFR renal function test result means can help you have more informed conversations with healthcare professionals and feel calmer about your next steps.
At Health Screening Clinic in South Kensington, London, our nurse-led service provides testing and reporting only. We do not offer diagnosis, treatment, or prescriptions. The information below is designed to help you understand your results in context, not to replace professional medical advice.
In This Article
What Is an eGFR Renal Function Test?
The eGFR renal function test is a calculated estimate of your glomerular filtration rate — the speed at which your kidneys filter waste products from the blood. It is reported in millilitres per minute per 1.73 m² of body surface area (mL/min/1.73 m²). In the UK, eGFR is included in virtually every standard kidney function blood panel and is one of the key markers laboratories use to flag potential changes in renal health.
Unlike a direct measurement, eGFR is derived from your serum creatinine result, adjusted for age and sex. It provides a practical, widely accepted estimate of how effectively the kidneys are working. For a broader overview of how kidney biomarkers fit together, our guide to monitoring renal filtration efficiency explains how eGFR, creatinine, and urea interact.
Practical Insight: eGFR is not a diagnosis in itself. It is a screening estimate that may prompt further review if the value falls outside expected ranges or changes significantly over time.
How Is eGFR Calculated?
In UK laboratories, eGFR is most commonly calculated using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. This formula uses:
- Serum creatinine: a waste product from normal muscle metabolism that the kidneys filter from the blood.
- Age: kidney filtration naturally changes with age, and the formula accounts for this.
- Sex: average creatinine production differs between males and females, so the calculation is adjusted accordingly.
The result is reported automatically by the laboratory whenever creatinine is measured. You do not need to request eGFR separately — it is standard practice in UK kidney function panels as part of broader screening such as our full body MOT packages, all of which include kidney function markers.
Practical Insight: Because eGFR is calculated from creatinine, anything that temporarily raises creatinine — such as intense exercise, high-protein meals, or dehydration — can sometimes affect the result.
eGFR Stages and What They May Indicate
In the UK, eGFR results are often interpreted using the internationally recognised CKD staging framework. It is important to note that a single eGFR reading does not confirm chronic kidney disease — staging typically requires sustained results over at least three months, interpreted alongside clinical context.
| Stage | eGFR (mL/min/1.73 m²) | What It May Suggest |
|---|---|---|
| G1 | 90 or above | Normal or high filtration rate |
| G2 | 60–89 | Mildly reduced filtration — often age-related and may not indicate disease |
| G3a | 45–59 | Mild to moderate reduction — may warrant monitoring and further review |
| G3b | 30–44 | Moderate to severe reduction — medical advice is generally recommended |
| G4 | 15–29 | Severely reduced filtration — further medical assessment is usually appropriate |
| G5 | Below 15 | Very severe reduction — urgent medical care may be needed |
Many adults in their 50s, 60s, and beyond will show an eGFR in the G2 range without any underlying kidney disease. A mildly reduced eGFR in isolation does not automatically indicate a problem, which is why context, trends, and supporting markers matter. For more on how to read blood test ranges without unnecessary worry, see our guide to understanding reference ranges in blood tests.
Practical Insight: A single eGFR of 62 in a healthy 65-year-old may carry very different significance from a sudden drop to 62 in a 35-year-old. Always consider the number alongside age, baseline, and clinical backdrop.
Factors That Can Affect Your eGFR Result
Because eGFR is calculated from creatinine, several non-kidney factors can influence the number you see on your report:
- Muscle mass: people with higher muscle mass may have naturally higher creatinine, which can lower the eGFR estimate without reflecting true kidney impairment.
- Hydration status: dehydration can temporarily increase creatinine concentration in the blood.
- Recent exercise: intense physical activity in the hours before testing may elevate creatinine levels.
- Diet: a high-protein meal the evening before a blood test can sometimes influence the reading.
- Certain medications: some commonly used medications may affect creatinine clearance, which a healthcare professional can advise on.
Proper preparation before a blood test helps reduce the chance of a misleading result. Our article on common mistakes that affect blood test results covers practical steps to support more reliable readings.
Practical Insight: If your eGFR seems unexpectedly low, consider whether hydration, exercise, or diet may have played a role. A repeat test under better-controlled conditions may give a more representative picture.
Who Should Consider an eGFR Renal Function Test?
In the UK, kidney function testing is widely recommended for adults with specific risk factors, and it is routinely included in most general health screening panels. You may particularly benefit from knowing your eGFR if you:
- Are over 40 and building a preventive health baseline.
- Have diabetes, elevated blood sugar, or a family history of metabolic disease.
- Have high blood pressure or cardiovascular risk factors.
- Have a close family history of kidney disease.
- Have received a borderline or abnormal kidney result in the past and want to monitor the trend.
- Are using preventive screening to understand organ function alongside cholesterol, liver, and glucose markers.
At Health Screening Clinic, kidney function markers including eGFR, creatinine, urea, and electrolytes are included in our Basic, Advanced, and Platinum Full Body MOT screening packages, alongside liver, lipid, and glucose testing. For men who want to go beyond organ function markers, our guide to the Male Hormonal Health Screening package explains how endocrine markers can complement kidney and metabolic testing.
Practical Insight: Kidney function tends to change quietly. Many people who feel perfectly well discover a mildly reduced eGFR on routine screening, which is exactly the scenario where early awareness can be most useful.
NHS vs Private Kidney Testing in London
Understanding how private and NHS kidney testing compare can help you decide which route suits your situation.
| Feature | NHS Kidney Testing | Private Screening (London) |
|---|---|---|
| Access | Usually requires clinical indication or chronic disease pathway | Available on request for preventive health |
| Waiting time | Variable, depending on local capacity | Typically same-week or next-day appointments |
| Breadth of panel | Targeted to clinical question | Kidney markers often included within wider health panels |
| Written report | Results shared via GP | Detailed report provided directly to the patient |
| Follow-up | GP manages ongoing care | Results can be shared with GP or healthcare professional for further advice |
Neither route replaces the other. NHS care is essential for ongoing clinical management, while private testing in London can provide earlier access to kidney markers as part of a broader preventive screening approach. Many people use private blood tests to establish a baseline and then share any flagged findings with their healthcare provider.
How Often Should You Repeat an eGFR Renal Function Test?
The right testing frequency depends on your health background and what previous results have shown:
- Baseline only: if you have no risk factors and results are within normal range, a one-off test may be sufficient to establish your starting point.
- Annual monitoring: often useful for adults with diabetes, high blood pressure, cardiovascular risk, or family history of kidney disease.
- Earlier repeat testing: may be appropriate after a borderline eGFR, a period of illness, significant dehydration, or a notable change from a previous result.
Practical Insight: A single eGFR reading is a snapshot. Two or three results over several months give a far more reliable picture of whether kidney function is stable or changing.
Frequently Asked Questions
What does an eGFR renal function test actually measure?
An eGFR renal function test estimates how efficiently your kidneys filter waste from the blood. The result is calculated from your serum creatinine level, age, and sex, and it is reported in mL/min/1.73 m². It provides a practical snapshot of kidney filtration performance at the time of the test.
What is a normal eGFR result in the UK?
In the UK, an eGFR of 90 or above is generally considered normal. Values between 60 and 89 may be entirely normal for older adults and do not necessarily indicate disease. The result should always be interpreted alongside age, clinical context, and any previous readings for meaningful comparison.
Can my eGFR result be affected by what I eat or drink?
Yes. Dehydration, a high-protein meal, or intense exercise before the test can temporarily raise creatinine levels, which may lower your eGFR renal function test estimate. Proper hydration and following pre-test instructions can help ensure a more accurate reading.
Does a low eGFR mean I have kidney disease?
Not necessarily. A single low eGFR result may reflect temporary factors such as dehydration, muscle mass variation, or recent exercise. Chronic kidney disease staging usually requires sustained changes over at least three months. If your eGFR is unexpectedly low, a repeat test and medical advice are sensible next steps.
How is eGFR different from creatinine?
Creatinine is the raw blood marker measured during the test, reflecting waste from muscle metabolism. eGFR is a calculation derived from that creatinine result, adjusted for your age and sex, designed to estimate overall kidney filtration. Both are usually reported together in a UK kidney function panel.
Who should have their eGFR checked regularly?
Regular eGFR renal function testing may be particularly useful for adults over 40, people with diabetes or high blood pressure, those with a family history of kidney disease, and anyone who has previously received borderline kidney results. For many people, annual monitoring provides helpful trend data.
Can I get an eGFR test privately in London?
Yes. Private blood testing in London offers convenient access to eGFR renal function testing as part of wider health screening panels. At Health Screening Clinic in South Kensington, kidney function markers are included in all Full Body MOT packages, with results delivered via a detailed written report.
What should I do if my eGFR result is abnormal?
If your eGFR result falls outside the expected range, seeking medical advice is the most appropriate next step. A healthcare professional can assess the result alongside your full clinical picture, decide whether a repeat test is appropriate, and recommend any further steps. If symptoms are severe or rapidly worsening, urgent medical care should be sought.
Does eGFR naturally decline with age?
Yes. Kidney filtration rate tends to decrease gradually with age, and an eGFR in the 60–89 range is not uncommon in adults over 60. This natural decline does not always indicate kidney disease, which is why repeat testing and trend analysis over time are generally more informative than a single result.
Is eGFR included in a standard blood test at Health Screening Clinic?
Yes. eGFR is automatically calculated and reported as part of the kidney function panel in our screening packages. All Full Body MOT packages — Basic, Advanced, and Platinum — include eGFR alongside creatinine, urea, and electrolytes as standard kidney markers.
Taking a Measured Approach to Kidney Health
Understanding your eGFR renal function test result does not need to cause anxiety. For many people, the most valuable thing screening provides is a baseline — a reference point that makes future results easier to interpret. Whether your eGFR is well within range or slightly outside it, having the information gives you a clearer foundation for long-term wellbeing decisions.
If kidney health is something you would like to monitor proactively, a structured blood panel is a practical starting point. At Health Screening Clinic, our nurse-led team provides clear reporting to help support your awareness, with detailed written results you can share with any healthcare professional.
Disclaimer
This article is for educational and informational purposes only. It does not replace professional medical advice. Individual symptoms, health concerns, and test results should be assessed by an appropriate healthcare professional. Health Screening Clinic provides testing and reporting only and does not provide diagnosis, treatment, or prescriptions. No specific outcome is guaranteed or implied.
Written Date: 7 April 2026
Next Review Date: 7 April 2027