What does an eGFR (estimated Glomerular Filtration Rate) greater than 60 indicate?

Understanding eGFR >60 mL/min/1.73 m²

An estimated glomerular filtration rate (eGFR) greater than 60 mL/min/1.73 m² generally indicates normal or mildly decreased kidney function, which is not classified as chronic kidney disease (CKD) unless other markers of kidney damage are present. 1, 2

Normal eGFR Values and Interpretation

• A normal GFR is approximately 130 mL/min/1.73 m² for men and 120 mL/min/1.73 m² for women 1
• eGFR naturally declines with age at a rate of about 0.75 mL/min/year after age 30-40 1, 2
• According to KDIGO guidelines, kidney function is classified as:
  • eGFR ≥90 mL/min/1.73 m² = Normal kidney function (G1 if other markers of kidney damage exist)
  • eGFR 60-89 mL/min/1.73 m² = Mildly decreased function (G2 if other markers of kidney damage exist)
  • eGFR <60 mL/min/1.73 m² = Moderately to severely decreased function (G3a-G5) 2

Important Considerations

Complete Assessment Requires More Than Just eGFR

An eGFR >60 mL/min/1.73 m² alone is insufficient to rule out kidney disease. A complete kidney assessment should include:

• Urine albumin-to-creatinine ratio (ACR) to detect albuminuria 1, 2
• Assessment for other markers of kidney damage:
  • Abnormalities in imaging tests
  • Structural abnormalities
  • History of kidney transplantation 1, 2

Accuracy of eGFR Measurements

• The CKD-EPI equation is more accurate than the MDRD Study equation, especially for eGFR values >60 mL/min/1.73 m² 1, 3
• eGFR can fluctuate based on various factors:
  • Hydration status
  • Recent exercise
  • Infection or fever
  • Congestive heart failure
  • Marked hyperglycemia
  • Extremes of muscle mass or weight (obesity, amputees)
  • Non-steady state conditions like diabetes 1, 2

Clinical Implications

• For individuals with eGFR >60 mL/min/1.73 m² without other markers of kidney damage, annual monitoring of kidney function is generally sufficient 2
• Even with eGFR >60 mL/min/1.73 m², patients should be evaluated for:
  • Albuminuria (ACR ≥30 mg/g)
  • Risk factors for kidney disease (diabetes, hypertension)
  • Family history of kidney disease 1, 2

Age Considerations

• In adults older than 70 years, eGFR values below 60 mL/min/1.73 m² may be physiologically normal due to age-related decline 4
• The fixed cut-off of 60 mL/min/1.73 m² for defining CKD has been challenged as it may not adequately account for age-related changes 4

Prevention of Kidney Function Decline

Even with normal eGFR, preventive measures are important:

• Blood pressure control
• Diabetes management
• Maintaining healthy weight
• Adequate hydration
• Avoiding nephrotoxic medications when possible 2, 5

In summary, an eGFR >60 mL/min/1.73 m² indicates normal or mildly decreased kidney function, but a complete assessment including albuminuria and other markers of kidney damage is necessary for a comprehensive evaluation of kidney health.