Kidney result interpreter
eGFR by Age: Compare an Adult Result with Age-Group Averages
Put an adult eGFR result in age context while keeping population averages separate from CKD diagnostic criteria.
Age-based averages are population estimates, not diagnostic cutoffs. CKD staging uses eGFR ranges and evidence of kidney damage, not age alone.
How this tool works
The interpreter compares an adult result with the nearest age-group average published by the National Kidney Foundation: 116 for ages 20-29, 107 for 30-39, 99 for 40-49, 93 for 50-59, 85 for 60-69, and 75 for age 70 or older. These are descriptive population averages, not personalized targets or normal limits.
Kidney function often declines with age, but age does not erase the importance of a low or falling value. CKD evaluation uses the result over time together with urine albumin, other markers of kidney damage, medicines, illness, and the clinical setting.
How to use it
- Enter the age at the time of the blood test and the eGFR exactly as shown on the laboratory report.
- Read the result as an age-context comparison, not as a diagnosis or a prediction of future kidney function.
- Compare with earlier results from the same laboratory when possible and review urine albumin or other kidney tests with a clinician.
How to interpret the result
KDIGO G categories are not adjusted upward or downward for age: G1 is 90 or higher, G2 is 60-89, G3a is 45-59, G3b is 30-44, G4 is 15-29, and G5 is below 15 mL/min/1.73 m². In the absence of other evidence of kidney damage, G1 and G2 do not by themselves meet CKD criteria.
One result can change with hydration, acute illness, medicines, recent meat intake, exercise, and laboratory variation. A persistent change or a large unexpected fall deserves clinical review rather than interpretation against an age average alone.
Limitations and safety
- For adult educational use only. Pediatric kidney function requires pediatric equations and age-specific clinical assessment.
- The listed averages do not define an individual healthy range, treatment threshold, or expected rate of decline.
- Do not delay medical care for symptoms or a rapidly changing result because the value appears close to an age-group average.
Sources and method
Formula and interpretation checked against the following primary or authoritative sources. Editorial review date: September 9, 2026.