eGFR (Estimated Filtration Rate)
An estimate of how many millilitres of blood your kidneys filter every minute.
Learn what egfr (estimated filtration rate) measures, why your healthcare professional may request this test, what typical reference ranges look like and what higher or lower results may sometimes indicate — in an educational context only.
The biology
Calculated from creatinine, age and sex. The single most useful number for kidney health.
Adjustments: Naturally declines about 1 mL/min/year after age 40.
Could a medication be shifting this result?
1 common medication or factor can move this test. Mark anything you take to see how it usually shifts the value. Stored on this device only.
Understand Your Laboratory Result
Enter your value to receive an educational explanation of what it may mean. This is not a diagnosis.
Developed using the expertise of a HCPC-registered Specialist Biomedical Scientist with more than 20 years of laboratory medicine experience.
Detectives Health explains laboratory data in plain English. It does not diagnose medical conditions, recommend treatments, or replace healthcare professionals.
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- Does not provide medical diagnoses
- Does not replace professional medical advice
- Results should always be interpreted in clinical context
- Critical values trigger safety guidance rather than interpretation
What out-of-range values can mean (general)
Background education only. A single laboratory value never points to one diagnosis. Always discuss results with your healthcare professional.
If the value is HIGHER than typical
RoutineNot clinically significant.
- Pregnancy
- Hyperfiltration in early diabetes
- None
- —
- —
Next steps: Usually no action.
If the value is LOWER than typical
Attention soonKidneys filtering less than expected for age.
- Diabetes
- High blood pressure
- Chronic kidney disease
- Fatigue
- Swelling, foamy urine
- Control salt, moderate protein
- Mediterranean pattern
- Control BP and sugar
- Avoid NSAIDs
Next steps: Below 60 — GP review for staging.
Why is this blood test important?
Healthcare professionals request eGFR (Estimated Filtration Rate) to help build a picture of how the body is functioning. It is one of many laboratory markers within the kidney function & electrolytes group and contributes to the wider assessment of health, alongside symptoms, examination and other investigations.
- Supports routine health checks and monitoring of long-term conditions.
- Helps evaluate how relevant organs and body systems are performing.
- Provides a baseline to compare with future results over time.
- Assists healthcare professionals in deciding whether further tests are needed.
Before interpreting your result
One laboratory result rarely tells the whole story. Healthcare professionals interpret blood tests alongside:
- symptoms
- age
- sex
- medications
- medical history
- previous laboratory results
- physical examination
- additional investigations
Understanding your result
The following categories are educational descriptions only — always discuss your result with a qualified healthcare professional.
A value within the reference range usually suggests the marker is behaving as expected for most healthy adults. Reference ranges vary between laboratories, populations and analytical methods.
A value close to the edge of the reference range may sometimes warrant repeat testing to confirm the finding, especially if you feel well and have no relevant symptoms.
Values above the typical range may reflect a variety of educational explanations — including recent lifestyle factors, medication, illness or underlying health conditions. Clinical review is needed to interpret meaning.
Values below the typical range may also have many educational explanations, from nutritional and lifestyle factors to specific medical conditions. A single low reading is rarely conclusive.
What can influence this result?
Many everyday factors can influence laboratory values. Understanding them can help you and your healthcare professional make sense of a result.
- Recent meals and fasting status
- Exercise before the test
- Stress levels
- Sleep and time of day
- Recent illness or infection
- Prescribed and over-the-counter medications
- Alcohol intake
- Smoking
- Hydration
- Pregnancy (where relevant)
Questions you may wish to discuss with your healthcare professional
- Do I need this test repeated?
- Should any additional laboratory tests be performed?
- How does this result compare with my previous results?
- Could any of my medications affect this result?
- What lifestyle changes may support healthier results?
- Are there other markers we should be monitoring together?
Related laboratory tests
Other markers within the kidney function & electrolytes group commonly reviewed alongside eGFR (Estimated Filtration Rate).
Healthy lifestyle
Lifestyle habits can support the body systems this test reflects. General wellbeing measures often have a measurable impact over time when maintained consistently.
- Balanced eating: a varied diet rich in vegetables, fibre and lean protein supports metabolic and organ health.
- Regular activity: aerobic and strength-based movement helps circulation and long-term marker stability.
- Restorative sleep: consistent sleep supports hormonal and inflammatory balance.
- Healthy weight: maintaining a stable, healthy weight often improves multiple laboratory markers.
- Not smoking: avoiding tobacco benefits nearly every organ system.
- Alcohol in moderation: lower intake reduces stress on the liver and metabolism.
- Stress management: mindfulness, breathing and rest can influence hormonal and inflammatory markers.
- Hydration: adequate fluids support kidney function and stable blood chemistry.
When should I seek urgent help?
Laboratory results alone are not an emergency, but seek urgent medical attention if abnormal results occur together with severe symptoms such as:
- collapse
- confusion or altered awareness
- severe chest pain
- severe breathlessness
- seizures
- loss of consciousness
UK: call NHS 111, or 999 if seriously unwell. Elsewhere: contact your GP or local emergency service.
Frequently asked questions
Why was this test requested?
eGFR (Estimated Filtration Rate) is often included as part of routine checks, condition monitoring or investigation of specific symptoms. Your healthcare professional can explain the reason in your case.
Can one abnormal result happen by chance?
Yes. Biological variation, timing, hydration and laboratory factors mean single out-of-range readings do occur in healthy people. Repeat testing is often used to confirm findings.
Why do laboratories use reference ranges?
Reference ranges represent values seen in most healthy people for a given population and method. They are guides, not diagnostic thresholds — interpretation always depends on clinical context.
Do I need to fast?
Some tests require fasting; others do not. Follow the specific instructions provided by your clinic or laboratory when the sample is arranged.
How often is this test repeated?
Repeat frequency depends on the reason for testing, any diagnosis being monitored and clinical judgement. Your healthcare professional will advise the interval that fits your situation.
Developed under Biomedical Science Leadership
This educational content has been developed and reviewed by the Detectives Health Professional Team under the scientific leadership of Steve Diongo, Founder of Detectives Health and HCPC-Registered Specialist Biomedical Scientist.
Educational content follows recognised laboratory standards, current scientific evidence and professional best practice.
Learn More About Laboratory Results
Detectives Health provides blood test interpretation and laboratory result explanation to help you understand blood test results. If you have ever wondered "what do my lab results mean?" — our goal is to ensure blood test results explained in plain English, with educational context and aligned guidance.