The Natural Decline of eGFR with Age
Your kidneys contain tiny filtering units called nephrons, and with normal aging, there is a gradual and progressive loss of these nephrons. This leads to a decline in the kidneys' filtering capacity, which is reflected in a lower eGFR. Medical guidelines and healthcare professionals recognize this decline and interpret eGFR results with a person's age in mind.
For a 70-year-old, the 'normal' eGFR is not the same as for a 30-year-old. While an eGFR over 90 mL/min/1.73 m² is considered normal for a young adult, a healthy 70-year-old may have an eGFR that falls in the 60-89 range without it automatically signifying kidney disease, especially if no other markers of kidney damage (like protein in the urine) are present.
Factors Influencing a 70-Year-Old's eGFR
Beyond the natural aging process, several other factors can affect an eGFR reading in older adults. Some of these are temporary, while others can indicate underlying health issues. A healthcare provider will consider the full clinical picture, not just the single eGFR number.
- Chronic Health Conditions: High blood pressure and diabetes are two of the most common causes of kidney disease and are more prevalent in older populations. Poorly managed conditions can accelerate the decline in kidney function.
- Medications: Certain medications, including over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, can affect kidney function, especially with regular use. Dosages for many medications are also adjusted based on reduced kidney function in seniors.
- Hydration Status: Dehydration can temporarily lower eGFR. It's especially important for seniors to stay well-hydrated, though those with advanced kidney or heart disease may need to monitor their fluid intake carefully.
- Creatinine Levels: The eGFR is estimated from a blood creatinine test. Since muscle mass naturally decreases with age, a 70-year-old may have lower overall creatinine levels, which can influence the eGFR calculation.
- Lifestyle: Diet and exercise can play a role. A diet high in salt and processed foods can harm kidneys over time, while regular physical activity supports overall cardiovascular and kidney health.
Interpreting an eGFR Result: Normal vs. Concerning
It is crucial to understand that an eGFR value must be interpreted in context. A slightly lower eGFR in a 70-year-old with no symptoms and stable readings over time may not be a major concern, while a rapid drop could indicate a problem.
- eGFR 60-89: For a 70-year-old, this range can often be normal. However, doctors will look for other signs of kidney damage, particularly protein or albumin in the urine, to confirm if early-stage kidney disease (CKD) is present. Monitoring is key.
- eGFR 15-59: This range usually indicates kidney disease. If an eGFR remains below 60 for more than three months, it is a strong indicator of moderate-to-severe kidney disease. At this stage, regular monitoring and management are necessary, often involving a kidney specialist (nephrologist).
- eGFR below 15: This indicates kidney failure, requiring treatment options like dialysis or a kidney transplant.
Chronic Kidney Disease (CKD) Stages and eGFR
To standardize care, the National Kidney Foundation classifies chronic kidney disease into five stages based on eGFR values. This helps healthcare providers plan treatments and monitor progression effectively.
| CKD Stage | Description | eGFR (mL/min/1.73 m²) |
|---|---|---|
| 1 | Kidney damage with normal or high GFR | ≥ 90 |
| 2 | Kidney damage with mildly decreased GFR | 60–89 |
| 3A | Mild-to-moderate decrease in GFR | 45–59 |
| 3B | Moderate-to-severe decrease in GFR | 30–44 |
| 4 | Severe decrease in GFR | 15–29 |
| 5 | Kidney failure | < 15 |
It's important to remember that for an older person, a value that falls into Stage 2 or 3A might be a normal age-related change rather than an urgent medical issue, provided there is no evidence of actual kidney damage.
How to Support Healthy Kidney Function as a Senior
Regardless of your current eGFR, there are proactive steps a 70-year-old can take to protect and support kidney function.
- Manage Underlying Conditions: Keep blood sugar and blood pressure under control with prescribed medication, diet, and regular monitoring.
- Adopt a Kidney-Friendly Diet: Limit sodium, saturated fats, and processed foods. Focus on a plant-based diet rich in fruits, vegetables, and whole grains. A dietitian can provide personalized guidance.
- Stay Hydrated: Drink an adequate amount of water throughout the day. Your healthcare provider can advise on the right amount for your specific health needs.
- Exercise Regularly: Aim for regular physical activity like walking, swimming, or yoga. This helps manage weight, blood pressure, and blood sugar.
- Use Medications Cautiously: Consult with a healthcare provider before taking over-the-counter pain relievers like NSAIDs. Discuss all medications and supplements to ensure they are kidney-safe.
- Avoid Smoking and Limit Alcohol: Both smoking and excessive alcohol consumption are detrimental to kidney health. Quitting smoking is one of the most impactful steps you can take.
When to See a Doctor
While a lower eGFR can be normal with age, it's vital to seek medical advice for new or worsening symptoms. Signs of a potential kidney issue include persistent fatigue, swelling in the ankles or hands, changes in urination, or nausea. Regular check-ups with your doctor, including blood and urine tests, are essential for monitoring kidney health.
For more in-depth information and resources on managing kidney health, a great resource is the National Kidney Foundation.
Conclusion
While the question of what is a normal eGFR for a 70 year old does not have a single answer, it is clear that lower readings are expected due to the natural aging process. What matters most is the context of the reading and its stability over time. By focusing on a healthy lifestyle and working closely with healthcare professionals to manage underlying conditions, a 70-year-old can proactively support their kidney health for many years to come. Remember, a single number is just one part of your overall health picture.
