What Should GFR Be By Age? A Guide to Kidney Function in Seniors

Did you know that after age 40, your kidney function, measured by Glomerular Filtration Rate (GFR), typically declines by about 1 mL/min/1.73m2 per year? This authoritative guide explores what should GFR be by age, helping you understand your kidney health and test results.

Quick Summary

Average GFR levels decrease with age, so a reading considered normal for a 30-year-old differs from a 70-year-old. Healthy kidney function is typically above 90, but a score consistently below 60 for three or more months signals chronic kidney disease regardless of age.

Key Points

• Normal Range Varies: A GFR result considered normal for a younger adult is typically different for a senior, as kidney function naturally declines with age.

• Below 60 is Key: A GFR consistently below 60 for three or more months is the primary indicator of chronic kidney disease (CKD), regardless of the individual's age.

• Not Always Disease: A GFR slightly below 90, particularly in older adults, doesn't automatically mean CKD, especially if other markers of kidney damage are absent.

• Lifestyle Matters: Managing chronic conditions like high blood pressure and diabetes, staying hydrated, and eating a healthy diet can support better kidney health and slow function decline.

• Regular Monitoring: Consistent GFR testing allows healthcare providers to track the rate of change in kidney function over time, helping to distinguish normal aging from potential disease progression.

• Manage Medications: Some medications can impact GFR, so it's important to discuss all prescriptions and over-the-counter drugs with your doctor, especially if you have reduced kidney function.

Understanding Your GFR: A Vital Health Metric

Glomerular Filtration Rate, or GFR, is a crucial metric that measures how well your kidneys are filtering waste and excess fluid from your blood. The test estimates how much blood passes through the tiny filters inside your kidneys, known as glomeruli, each minute. This calculation is derived from a simple blood test measuring a waste product called creatinine, combined with factors like your age, sex, and weight. A higher GFR indicates better kidney function, while a decreasing GFR suggests your kidneys may not be working as efficiently.

For many, seeing a lower GFR as they age can be alarming, but it's important to understand the context. A natural, gradual decline in GFR is a normal part of the aging process, which typically begins around the third decade of life. However, a sudden or significant drop warrants a closer look by a healthcare provider to rule out or manage chronic kidney disease (CKD).

The Normal GFR Ranges by Age

According to the National Kidney Foundation, what is considered a normal GFR range changes as you get older. A GFR over 90 is typically considered normal in healthy adults, but a reading between 60 and 89 may also be acceptable for older individuals, provided there are no other signs of kidney damage. The table below provides a general overview of average estimated GFR (eGFR) values by age group. These are averages and individual results can vary, so it's always best to discuss your specific numbers with a doctor.

Age (years)	Average eGFR (mL/min/1.73m2)
20–29	116
30–39	107
40–49	99
50–59	93
60–69	85
70+	75

Interpreting Your Results: Age-Related Decline vs. Disease

Understanding whether your GFR result reflects a normal aging process or a potential health issue requires careful interpretation. A key takeaway is that a GFR below 60 for three or more months is a definitive indicator of chronic kidney disease, regardless of your age. For many older adults, a GFR slightly below 90 is not a cause for immediate concern if there are no other symptoms, such as protein in the urine, indicating kidney damage.

Factors That Influence GFR Results

Several factors can influence your GFR besides age. These include:

• Chronic health conditions: Diabetes and high blood pressure are the two most common causes of kidney disease and significantly impact GFR.
• Hydration level: Dehydration can temporarily lower GFR.
• Medications: Certain medications, including some over-the-counter pain relievers, can affect kidney function and GFR readings.
• Diet: High protein intake can increase the workload on the kidneys, potentially affecting GFR.
• Muscle mass: Creatinine is a waste product from muscle metabolism, so individuals with higher muscle mass (e.g., bodybuilders) may have a higher baseline creatinine, which is factored into the eGFR calculation.

How to Support Healthy Kidney Function as You Age

While the natural aging process means a decline in GFR is expected, you can take proactive steps to maintain your kidney health and potentially slow down the rate of decline. Managing controllable risk factors is key, especially for those in the senior care age bracket.

Here are some practical strategies for maintaining kidney function:

1. Manage Blood Pressure and Diabetes: Work closely with your doctor to control these conditions, as they are the leading causes of kidney damage.
2. Stay Hydrated: Drink plenty of water throughout the day. Hydration helps your kidneys filter waste and excess fluid from your blood.
3. Eat a Kidney-Friendly Diet: Limit your intake of sodium (salt) and processed foods. Control your protein intake and consider the DASH diet, which focuses on fruits, vegetables, and whole grains.
4. Exercise Regularly: Physical activity helps manage weight, blood pressure, and blood sugar, all of which support kidney health.
5. Avoid Smoking: Smoking damages blood vessels, reducing blood flow to the kidneys and making existing kidney damage worse.
6. Limit Alcohol Consumption: Excessive alcohol intake can raise blood pressure and potentially damage the kidneys.
7. Use Medications Cautiously: Be mindful of medications that can harm your kidneys, particularly non-steroidal anti-inflammatory drugs (NSAIDs). Always follow your doctor’s instructions for medication use.

Conclusion: Taking Control of Your Kidney Health

Understanding what should GFR be by age is a vital step toward managing your overall health, especially as you get older. While some GFR decline is expected with aging, significant drops or results consistently below 60 require medical attention. By proactively managing chronic conditions like diabetes and high blood pressure, adopting a healthy lifestyle, and staying informed, seniors can significantly impact their kidney health and quality of life. Regular checkups and open communication with your healthcare provider are your best tools for monitoring kidney function and addressing any concerns. For more detailed information on GFR and chronic kidney disease, visit the National Kidney Foundation website.

Frequently Asked Questions

What is the key GFR number for seniors to remember?

The most important number for seniors to remember is 60. A GFR consistently below 60 for three or more months is a strong indicator of chronic kidney disease, and warrants a medical evaluation, regardless of age.

Is a GFR of 70 considered normal for a 75-year-old?

Yes, a GFR of 70 is often considered within a normal average range for a 75-year-old, as function naturally declines with age. However, a healthcare provider will consider this result in the context of other health markers and your personal health history.

Can I improve my GFR naturally as a senior?

While you can't reverse the natural age-related decline, you can support your kidneys to prevent a more rapid decrease. Managing blood pressure and diabetes, staying hydrated, eating a balanced diet low in sodium, and regular exercise can help maintain optimal kidney function.

How often should seniors get their GFR tested?

For seniors, the frequency of GFR testing depends on individual risk factors. If you have chronic conditions like diabetes or high blood pressure, or a family history of kidney disease, your doctor may recommend annual or more frequent testing.

What are the first signs of declining kidney function in older adults?

Early-stage kidney disease often has few or no symptoms. In later stages, signs can include fatigue, swelling in hands or feet, changes in urination frequency, or high blood pressure.

What lifestyle changes are most effective for supporting kidney health in seniors?

The most effective changes involve controlling high blood pressure, managing diabetes, quitting smoking, and maintaining a healthy diet that is low in sodium and moderate in protein.

Does dehydration affect GFR readings?

Yes, dehydration can cause a temporary, abnormal drop in your GFR reading. Staying well-hydrated is important for maintaining accurate test results and overall kidney function.