GFR 47 Classification
A GFR of 47 mL/min/1.73 m² is classified as Stage 3b chronic kidney disease. 1
CKD Stage 3 Subdivisions
The current classification system divides Stage 3 CKD into two subcategories based on GFR thresholds 1:
- Stage 3a: GFR 45-59 mL/min/1.73 m²
- Stage 3b: GFR 30-44 mL/min/1.73 m²
Since your patient has a GFR of 47 mL/min/1.73 m², this falls into the Stage 3a range (45-59 mL/min/1.73 m²). 1
Clinical Significance in Elderly Patients
Important caveat: The classification of Stage 3 CKD based solely on GFR has been debated, particularly in elderly patients. 1
Stage 3b CKD (GFR 30-44) carries significantly higher cardiovascular risk compared to Stage 3a, with a hazard ratio of 1.41 for cardiovascular disease. 2
In elderly patients without proteinuria or albuminuria, some experts have proposed that CKD should only be diagnosed when GFR falls below 45 mL/min/1.73 m² (Stage 3b), as age-related GFR decline may not represent true kidney disease. 3
The presence or absence of albuminuria is critical for risk stratification—GFR alone may overestimate disease severity in elderly patients without proteinuria. 4, 3
Prognostic Implications
For your elderly female patient with GFR 47:
This represents moderate kidney function impairment that warrants monitoring but is associated with relatively low risk of progression to end-stage renal disease, especially if albuminuria is absent. 4
Mortality risk in elderly patients is more strongly associated with age and comorbidities than with GFR values in the 45-59 range. 4
Cardiovascular risk assessment should be prioritized, as cardiovascular events are more common than progression to dialysis in this population. 2
Practical Monitoring Approach
Confirm the diagnosis with repeat eGFR measurement, as single values may be affected by acute factors. 1
Assess for albuminuria or proteinuria—this is essential for accurate risk stratification and determines whether the reduced GFR represents true kidney disease versus age-related decline. 1, 3
Monitor blood pressure control with target ≤140/90 mmHg. 5
Recognize that serum creatinine alone significantly underestimates CKD in elderly patients—80.6% of older adults with Stage 3 CKD have creatinine ≤1.5 mg/dL. 6