Normal GFR Range in Adults
The normal GFR range in healthy young adults is approximately 100-130 mL/min/1.73 m² for men and 90-120 mL/min/1.73 m² for women, with values remaining stable until age 40 years, after which physiological decline begins. 1, 2
Age and Sex-Specific Normal Values
- Young adults (under 40 years): Mean GFR is approximately 107 mL/min/1.73 m² and remains constant until age 40 in both sexes 2
- Men: Normal range of 120-130 mL/min/1.73 m² in young adults 1
- Women: Normal range of 90-120 mL/min/1.73 m² in young women 1
- After age 40: GFR begins physiological decline in both men and women 2, 3
- Older adults (>70 years): Values below 60 mL/min/1.73 m² may be considered normal due to age-related decline 3
Clinical Thresholds for Kidney Function Assessment
GFR ≥90 mL/min/1.73 m² represents optimal kidney function and is the recommended threshold for living kidney donors 1
GFR 60-89 mL/min/1.73 m² indicates mildly decreased kidney function but may be normal for older adults 1
GFR <60 mL/min/1.73 m² represents loss of half or more of normal adult kidney function and defines chronic kidney disease (CKD) when persistent for ≥3 months 4, 1, 5
- This threshold affects approximately 17% of persons older than 60 years 1
- The subdivision of stage 3 CKD into G3a (45-59 mL/min/1.73 m²) and G3b (30-44 mL/min/1.73 m²) reflects different risk profiles 4
Critical Clinical Context and Interpretation
GFR >60 mL/min/1.73 m² does not exclude kidney disease if other markers of kidney damage are present, such as albuminuria (ACR >30 mg/g) or structural abnormalities on imaging 4, 1, 6
The diagnosis of CKD requires either:
- GFR <60 mL/min/1.73 m² for >3 months, OR
- GFR ≥60 mL/min/1.73 m² with evidence of kidney damage (albuminuria, structural abnormalities) for >3 months 4, 5
Common Pitfalls to Avoid
Never use serum creatinine alone to assess kidney function; always calculate GFR 1
Do not diagnose CKD based on a single GFR measurement—persistent abnormalities for ≥3 months are required 1, 5
Be aware of factors affecting eGFR accuracy:
- Extremes of muscle mass or body weight can produce inaccurate estimates 1
- Non-steady state conditions (acute illness, recent surgery) may yield unreliable results 1
- Hydration status significantly impacts measurements 1
- Creatinine is influenced by diet and muscle mass, while cystatin C is produced by all nucleated cells 5
Age considerations are critical: The fixed cut-off of 60 mL/min/1.73 m² may inappropriately classify elderly patients as having CKD when values represent normal age-related decline 3