Can eGFR increase with age? Understanding the Facts About Kidney Function

Healthy kidney function naturally declines as a person gets older, with the average eGFR dropping by approximately 1 mL/min per year after age 40. Given this physiological reality, many ask: Can eGFR increase with age? For most, the answer is complex, focusing more on slowing decline than achieving a permanent increase.

Quick Summary

An increase in eGFR with age is highly unlikely for most people as kidney function naturally diminishes over time, but temporary improvements can occur, and proactive healthy habits can significantly slow the rate of decline.

Key Points

• Natural Decline is Normal: eGFR typically decreases with age, even in healthy individuals, and a permanent increase is unlikely.

• Focus on Management, Not Reversal: The goal for older adults should be to slow the natural decline of eGFR through healthy habits and medical management.

• Lifestyle is Key: Maintaining a healthy diet, exercising regularly, and managing conditions like high blood pressure and diabetes are crucial for preserving kidney function.

• Comorbidities Accelerate Decline: Conditions like diabetes and hypertension are major factors that can speed up the rate of eGFR reduction.

• Accurate Interpretation is Vital: A low eGFR in an older person doesn't always signify severe CKD; it should be interpreted alongside other tests and clinical factors.

• Temporary Increases Can Occur: Transient increases in eGFR may follow an acute illness like dehydration, but this doesn't indicate a reversal of age-related changes.

The Truth About Age and Kidney Health

While the concept of increasing eGFR with age is appealing, it's largely a misconception. The natural aging process leads to a gradual reduction in the number of functioning nephrons, the tiny filtering units within the kidneys. This decline is universal and expected, even in healthy individuals without other health conditions. A key aspect of managing kidney health in later life is to understand this natural progression and focus on interventions that help preserve existing kidney function rather than trying to reverse the biological effects of aging.

Factors That Influence eGFR in Seniors

The rate and severity of eGFR decline can be influenced by a variety of factors beyond normal aging. By understanding and managing these elements, older adults can play an active role in protecting their kidney health.

Comorbidities and Chronic Conditions

• High Blood Pressure (Hypertension): Uncontrolled high blood pressure is a leading cause of kidney disease and significantly accelerates eGFR decline. Consistent monitoring and management are crucial.
• Diabetes: High blood sugar levels can damage the blood vessels in the kidneys over time, impairing their filtration abilities. Proper management of blood glucose is essential for slowing down kidney damage.
• Inflammation and Oxidative Stress: Chronic low-grade inflammation, common in older age, can harm kidney tissue. Similarly, oxidative stress contributes to cellular damage and reduced kidney function.

Lifestyle Choices

• Dietary Habits: High-sodium diets can increase blood pressure and strain the kidneys. Conversely, a balanced diet rich in plant-based foods can support kidney function. For those with reduced function, a renal dietitian may recommend specific protein, phosphorus, and potassium limits.
• Physical Activity: Regular, moderate exercise helps control blood pressure, manage weight, and improve cardiovascular health, all of which benefit the kidneys.
• Smoking: Tobacco use damages blood vessels throughout the body, including those in the kidneys, and can worsen existing kidney disease.
• Medication Use: Long-term use of certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can harm the kidneys, especially in older adults. It is critical to discuss all medications with a healthcare provider.

Is Temporary eGFR Improvement Possible?

While a sustained increase in eGFR is generally not expected with age, a temporary bump in the number is possible in specific scenarios. For instance, following an episode of acute kidney injury (AKI)—a sudden, temporary drop in kidney function—a person's eGFR might improve once the underlying cause is treated. These fluctuations can also occur due to dehydration or changes in diet or medication, but they do not signify a reversal of age-related decline or established chronic kidney disease.

The Difference Between Normal Aging and Chronic Kidney Disease

It's important for older adults and their healthcare providers to distinguish between the expected, gradual decline of aging and the more serious condition of chronic kidney disease (CKD). The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines define CKD as an eGFR below 60 mL/min for three or more months, or evidence of kidney damage regardless of the eGFR level.

To help clarify an individual's status, some experts have proposed using age-adapted thresholds for eGFR. Because a lower eGFR is normal in older adults, a value between 45 and 59 mL/min may not carry the same risk in an 80-year-old as it would in a 40-year-old. For this reason, supplementary tests, such as measuring cystatin C levels or checking for protein in the urine, can provide a more accurate assessment.

Comparison: Interpreting eGFR in Older vs. Younger Adults

Feature	Younger Adults (<65 years)	Older Adults (≥65 years)
Expected eGFR	Naturally higher, with a value above 90 typically considered normal.	Naturally lower due to age-related nephron loss; values below 60 are more common.
Significance of eGFR < 60	Often a clear indicator of chronic kidney disease or significant damage.	Can be a sign of CKD but is not always indicative of increased mortality risk on its own. May reflect normal aging.
Diagnostic Approach	A low eGFR is often enough for a CKD diagnosis, particularly when it is persistent.	Doctors should consider the eGFR in context with other factors like albuminuria, comorbidities, and overall health to determine clinical significance.
Optimal Markers	Creatinine-based eGFR equations are often sufficient.	Combining creatinine and cystatin C provides a more accurate estimate of true kidney function.

How to Slow the Decline of eGFR

Instead of aiming for an unlikely increase, focus on these strategies to preserve kidney function as long as possible. The National Kidney Foundation offers a wealth of resources on this topic: Protecting Your Kidneys.

1. Manage Underlying Conditions: Adhere strictly to treatment plans for conditions like diabetes and high blood pressure. Keeping these under control is the single most effective way to protect kidney health.
2. Adopt a Kidney-Friendly Diet: Focus on whole, unprocessed foods, and limit sodium intake. A renal dietitian can provide a personalized plan if needed.
3. Stay Hydrated: Drinking enough water helps the kidneys filter waste products efficiently. Discuss appropriate fluid intake with your doctor, as needs vary, especially for those with existing conditions.
4. Exercise Regularly: Aim for at least 30 minutes of moderate activity most days of the week. This improves cardiovascular health and helps manage blood pressure and weight.
5. Avoid Kidney-Damaging Medications: Be cautious with NSAIDs and other over-the-counter painkillers. Always consult a healthcare provider before starting new medications or supplements.
6. Quit Smoking and Moderate Alcohol: Both smoking and excessive alcohol consumption negatively impact kidney function and overall health.

Conclusion

While a significant, permanent increase in eGFR with age is not a realistic expectation, this fact should not be a cause for discouragement. The focus should shift to proactive management and lifestyle choices that preserve existing kidney function and slow its natural decline. By working closely with a healthcare team to control comorbidities and make informed lifestyle decisions, older adults can significantly influence their long-term renal health and overall well-being. Understanding how to interpret eGFR results in the context of advanced age is the first step towards taking control of your health.

Frequently Asked Questions

Is a low eGFR always a sign of chronic kidney disease (CKD) in older adults?

Not necessarily. A moderately low eGFR can be a natural result of the aging process. A diagnosis of CKD depends on additional factors, such as the eGFR staying below 60 for three months or more, or if there is other evidence of kidney damage like albumin in the urine.

What is the primary reason that an eGFR number doesn't increase with age?

The primary reason is the physiological process of aging, which involves a gradual and irreversible loss of functioning nephrons, the filtering units in the kidneys. This leads to a progressive decline in the kidney's filtering capacity over time.

Can diet and exercise stop my eGFR from declining as I age?

While a completely age-related decline cannot be stopped, a healthy diet and regular exercise can significantly slow down the rate of eGFR decline. These habits help manage conditions like high blood pressure and diabetes, which are major risk factors for kidney disease.

How can I tell if my eGFR decline is normal or a cause for concern?

Consult with your healthcare provider. They will evaluate your eGFR trend over time, along with other test results like urine albumin and your overall health history. A single low reading may not be as concerning as a persistent downward trend.

Do all eGFR equations factor in age?

Yes, standard eGFR calculations, like the CKD-EPI equation, include age, sex, and serum creatinine levels to estimate kidney function. The fact that age is a factor in the calculation acknowledges the expected decline in kidney function over time.

Are there specific medications I should be cautious of if I have a lower eGFR due to age?

Yes. Medications like NSAIDs (e.g., ibuprofen) can be particularly damaging to kidneys, especially with age-related decline. You should always discuss your eGFR with your doctor to ensure that medication dosages are appropriate for your level of kidney function.

Why is it important to check for protein in my urine along with my eGFR?

Testing for albumin (a type of protein) in your urine, known as the uACR test, provides a more complete picture of your kidney health. An eGFR above 60 combined with albuminuria is an early sign of kidney damage, even if the eGFR number appears normal.

What is the role of cystatin C in estimating eGFR in older adults?

Because creatinine levels can be misleading in older adults with less muscle mass, cystatin C is a newer marker that may provide a more accurate estimate of GFR. Incorporating cystatin C into eGFR equations can improve diagnostic accuracy in older individuals.