1. Introduction: The Growing Burden of CKD in an Aging Society
Chronic Kidney Disease eGFR interpretation in elderly patients, With the rapid aging of populations worldwide, the prevalence of chronic kidney disease (CKD) among elderly patients is also increasing. Traditionally, CKD has been diagnosed when the estimated glomerular filtration rate (eGFR) falls below 60 mL/min/1.73m². However, distinguishing age-related decline in kidney function from pathological CKD remains a significant challenge.
Applying a strict eGFR <60 criterion to elderly individuals may lead to overdiagnosis, classifying age-related physiological decline as a disease. This article explores the importance of age-specific eGFR cutoffs, albuminuria, and comorbidities such as diabetes in diagnosing CKD in elderly patients.
2. eGFR Declines with Aging—Is It Always CKD?
(1) Understanding eGFR
- The estimated glomerular filtration rate (eGFR) is a key marker of kidney function, typically calculated using serum creatinine or cystatin C.
- While an eGFR below 60 mL/min/1.73m² is traditionally classified as CKD, aging must be considered when interpreting these values.
(2) The Problem with a Fixed eGFR <60 Criterion in Elderly Patients
- Among patients in their 70s and 80s, it is common to observe eGFR values between 50–55 mL/min/1.73m², even in the absence of significant complications.
- Using a fixed 60 mL/min/1.73m² threshold could lead to the misclassification of age-related decline as CKD, resulting in unnecessary tests and treatments.
3. Why Are Albuminuria and Comorbidities Important in CKD Diagnosis?
(1) The Role of Albuminuria (UACR)
- Albuminuria (urinary albumin-to-creatinine ratio, UACR) is a sensitive marker of kidney damage.
- If eGFR is low but albuminuria is absent, the decline may be due to natural aging rather than CKD. Conversely, patients with albuminuria, even with relatively preserved eGFR, have a higher risk of CKD progression.
(2) The Impact of Diabetes, Obesity, and Cardiovascular Risk
- Comorbid conditions such as diabetes, obesity, and hypertension can accelerate kidney function decline beyond what is expected with normal aging.
- Diabetes significantly increases the risk of albuminuria, making early detection and close monitoring essential for elderly diabetic patients.
(3) Greater eGFR Decline in Patients with Comorbidities
- Patients with diabetes, obesity, and microalbuminuria exhibit a more rapid eGFR decline than their healthy counterparts.
- Understanding eGFR trajectories over time is crucial to distinguishing between normal aging and pathological CKD.
4. Age-Specific eGFR Cutoffs: Benefits and Limitations
(1) Benefits
✔ Prevention of Overdiagnosis: Helps differentiate normal age-related eGFR decline from true CKD, avoiding unnecessary treatments.
✔ Personalized Risk Assessment: In an 80-year-old, an eGFR of 50 mL/min/1.73m² might be within an expected range, whereas the same value in a 40-year-old may indicate serious kidney disease.
(2) Limitations
❌ Lack of Official Guidelines: Leading organizations such as KDIGO still use a fixed eGFR threshold of 60 mL/min/1.73m² for CKD diagnosis.
❌ Risk of Missing Severe Cases: If age-specific cutoffs are too lenient, some patients who require dialysis or kidney transplantation may be overlooked.
❌ Individual Variability: Muscle mass, nutrition, medications, and overall health impact eGFR, making a one-size-fits-all approach problematic.
5. Practical Applications: How Should We Interpret eGFR in Elderly Patients?
5.1 Use KDIGO Standards with Additional Markers
- In clinical practice, eGFR <60 mL/min/1.73m² + albuminuria remains the primary CKD diagnostic criterion.
- However, in elderly patients, using age-specific eGFR cutoffs can help reduce overdiagnosis.
5.2 Comprehensive Risk Assessment: Comorbidities, Albuminuria, and Decline Rate
- Assessing diabetes, hypertension, cardiovascular disease, and albuminuria alongside eGFR provides a more accurate risk evaluation.
- The rate of eGFR decline over time is more important than a single measurement—gradual declines suggest aging, while rapid declines suggest pathology.
5.3 Managing CKD in Elderly Patients: Conservative vs. Dialysis Approaches
- Kidney transplantation is often not feasible in patients aged 65+, necessitating a careful approach to dialysis initiation.
- Lifestyle modifications, medication adjustments, and patient-centered care should be prioritized to maximize remaining kidney function.
- The decision between dialysis and conservative management should be made collaboratively between physicians and patients, considering quality of life and overall prognosis.
6. Conclusion: Moving Beyond a Fixed eGFR 60 Threshold
- Age-related eGFR decline is not always indicative of CKD, and a rigid application of the 60 mL/min/1.73m² threshold may lead to overdiagnosis.
- However, albuminuria, diabetes, cardiovascular conditions, and eGFR decline rates should be carefully evaluated before ruling out CKD.
- Age-specific eGFR cutoffs provide useful reference points but should not replace comprehensive patient evaluation.
Ultimately, a patient-centered approach—rather than relying solely on a single eGFR value—is the key to optimizing kidney disease management in elderly populations.
References
- Herold JM, et al. “Population-based reference values for kidney function and kidney function decline in 25- to 95-year-old Germans without and with diabetes.” Kidney International, 2024;106(4):699–711.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl, 2024;105(4S):S117–S314.
Disclaimer: This article summarizes research findings and clinical guidelines for general informational purposes only. For specific diagnosis and treatment, consult a medical professional.
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