Your doctor just told you your eGFR number and you are wondering if it is normal for your age. You are not alone. Estimated glomerular filtration rate, or eGFR, is the best single test for measuring how well your kidneys filter waste from your blood.
The tricky part is that “normal” eGFR changes as you get older. A reading of 85 might be perfectly healthy for someone who is 70 but could signal early trouble for a 30-year-old.
What Is eGFR and Why Does It Matter?
eGFR estimates how many milliliters of blood your kidneys filter per minute. It is calculated from your blood creatinine level, age, sex, and sometimes race using a standardized formula. The result is expressed in mL/min/1.73m².
Your kidneys filter about 200 liters of blood every day. When that filtering ability declines, waste products build up in your blood. eGFR catches this decline early, often years before you feel any symptoms.
Normal eGFR Levels by Age Group
The following ranges represent typical average eGFR values in healthy individuals without kidney disease. These are approximate midpoints based on population studies.
Ages 20 to 29
Average eGFR: approximately 116 mL/min/1.73m². Young adults generally have the highest kidney filtration rates. Values above 90 are considered normal. Readings consistently below 90 at this age warrant further testing.
Ages 30 to 39
Average eGFR: approximately 107 mL/min/1.73m². A slight decline from the twenties is expected. Kidney function decreases by roughly 1 mL/min/1.73m² per year after age 30 in healthy adults.
Ages 40 to 49
Average eGFR: approximately 99 mL/min/1.73m². Most adults in their forties still have eGFR values well above 90. Values in the 80s may be age-appropriate but should be monitored if risk factors like diabetes or hypertension are present.
Ages 50 to 59
Average eGFR: approximately 93 mL/min/1.73m². This is the decade when many people first see eGFR dip below 90 on routine bloodwork. A reading of 85 to 89 without protein in the urine is usually not cause for alarm.
Ages 60 to 69
Average eGFR: approximately 85 mL/min/1.73m². Many healthy adults in their sixties have eGFR values between 70 and 90. The key question is whether the number is stable or declining over time.
Ages 70 and Older
Average eGFR: approximately 75 mL/min/1.73m² and lower. It is common for healthy people over 70 to have eGFR readings between 60 and 80. An eGFR in the 50s or 60s in an 80-year-old with no proteinuria may represent normal aging rather than kidney disease.
CKD Stages Based on eGFR
Chronic kidney disease is classified into five stages based on eGFR values:
- Stage 1 (eGFR 90+): Normal or high kidney function with other evidence of kidney damage such as protein in urine
- Stage 2 (eGFR 60-89): Mildly reduced function with evidence of kidney damage
- Stage 3a (eGFR 45-59): Mild to moderate reduction in kidney function
- Stage 3b (eGFR 30-44): Moderate to severe reduction
- Stage 4 (eGFR 15-29): Severe reduction in kidney function
- Stage 5 (eGFR below 15): Kidney failure, dialysis or transplant may be needed
An important nuance: eGFR between 60 and 89 alone is not classified as CKD unless there is also evidence of kidney damage, such as albumin in the urine, structural abnormalities, or a history of kidney transplant.
When Should You Worry About Your eGFR?
A single low eGFR reading does not always mean kidney disease. Here are the situations that do warrant concern:
- eGFR below 60 confirmed on repeat testing: Two readings below 60 at least 90 days apart meet the criteria for CKD stage 3 or higher
- Rapid decline: A drop of more than 5 mL/min/1.73m² per year is faster than normal aging and needs investigation
- Protein in your urine: Even with a normal eGFR, persistent proteinuria signals kidney damage
- eGFR below 45: At this level, your risk of cardiovascular events and progression to kidney failure rises significantly
- You have diabetes or hypertension: These are the two leading causes of CKD and require closer monitoring of kidney function
Factors That Temporarily Affect eGFR
Several things can cause your eGFR to read lower than your actual kidney function:
- Dehydration: Not drinking enough water before your blood draw can raise creatinine and lower eGFR
- High-protein meal: Eating a large amount of cooked meat the night before can temporarily increase creatinine
- Intense exercise: Heavy weightlifting or endurance exercise within 24 hours of the test can elevate creatinine
- Creatine supplements: These directly raise blood creatinine levels and will lower your calculated eGFR
- Certain medications: Some drugs like trimethoprim and cimetidine interfere with creatinine secretion
If your eGFR comes back unexpectedly low, ask your doctor if any of these factors could explain the result before assuming you have kidney disease.
How to Protect Your Kidney Function
Whether your eGFR is normal or slightly low, these evidence-based strategies help preserve kidney function:
- Control blood pressure: Keep it below 130/80 if you have CKD. Hypertension is the second leading cause of kidney failure
- Manage blood sugar: If you have diabetes, keeping your A1C below 7% significantly slows kidney damage
- Stay hydrated: Drink enough water so your urine is light yellow. Chronic dehydration stresses the kidneys
- Limit NSAIDs: Ibuprofen and naproxen reduce blood flow to the kidneys. Use them sparingly, especially if your eGFR is already reduced
- Monitor your blood pressure at home: Use our blood pressure calculator to track your readings and understand your category
Understanding the CKD-EPI Equation
Most labs now use the 2021 CKD-EPI creatinine equation, which removed the race variable from the calculation. This change was made because the previous race adjustment was based on flawed assumptions and could delay diagnosis in Black patients.
The current formula uses creatinine, age, and sex. Some centers also use cystatin C, a different blood marker, either alone or combined with creatinine for a more accurate estimate.
If your lab report still shows a race-adjusted eGFR, ask your doctor about the updated formula.
Frequently Asked Questions
Is an eGFR of 58 bad?
An eGFR of 58 falls in the CKD stage 3a range. In a 75-year-old without diabetes or proteinuria, it may reflect normal aging. In a 45-year-old, it warrants further evaluation. Context matters more than the number alone.
Can eGFR go back up?
Yes, in some cases. If the low eGFR was caused by dehydration, medication, or an acute illness, it can recover. In early CKD, lifestyle changes and medication can stabilize or modestly improve eGFR. Advanced CKD is generally not reversible.
How often should eGFR be checked?
For healthy adults, eGFR is typically included in annual bloodwork. If you have CKD risk factors or a previously low reading, your doctor may check it every 3 to 6 months.
