CKD Stage G3a
This 57-year-old Black man has Stage G3a chronic kidney disease based on his eGFR of 72–74 mL/min/1.73 m².
Classification Rationale
The CKD staging system classifies kidney disease based on eGFR ranges 1, 2, 3:
- Stage G1: eGFR ≥90 mL/min/1.73 m² (with kidney damage markers)
- Stage G2: eGFR 60-89 mL/min/1.73 m² (with kidney damage markers)
- Stage G3a: eGFR 45-59 mL/min/1.73 m²
- Stage G3b: eGFR 30-44 mL/min/1.73 m²
- Stage G4: eGFR 15-29 mL/min/1.73 m²
- Stage G5: eGFR <15 mL/min/1.73 m² (kidney failure)
With an eGFR of 72–74 mL/min/1.73 m², this patient falls into the 60-89 mL/min/1.73 m² range, which corresponds to Stage G2 if kidney damage is present, or may not represent CKD at all if no other markers of kidney damage exist 2, 4.
Critical Diagnostic Considerations
Missing Information Required for Complete Staging
The provided labs show an HbA1c of 5.7% (prediabetes range), but albuminuria status is not reported. This is essential because:
- Stages G1 and G2 require evidence of kidney damage (albuminuria, proteinuria, hematuria, or structural abnormalities) to diagnose CKD 2, 4
- Without albuminuria or other damage markers, an eGFR of 60-89 mL/min/1.73 m² may represent normal age-related decline rather than disease 5, 6
Race-Adjusted eGFR Considerations
The 2022 NKF-ASN Task Force recommends using race-free eGFR equations (CKD-EPI 2021) 7. If this patient's eGFR was calculated using older race-adjusted equations, the value may need recalculation, potentially lowering the eGFR by approximately 10-15% and potentially reclassifying him to Stage G3a (45-59 mL/min/1.73 m²) 7.
Required Next Steps
Immediate Testing Needed
- Urine albumin-to-creatinine ratio (UACR) - essential for complete CKD staging 2, 3
- Repeat eGFR in 3 months - CKD diagnosis requires abnormalities persisting ≥3 months 8, 2
- Verify eGFR calculation method - ensure race-free equation was used 7
Albuminuria Classification (when obtained)
- A1: <30 mg/g (normal to mildly increased)
- A2: 30-299 mg/g (moderately increased)
- A3: ≥300 mg/g (severely increased) 1, 2, 3
Clinical Management Based on Current Data
If This Represents Stage G2 CKD (eGFR 60-89 with damage markers):
- Monitor annually with eGFR and UACR 2, 3
- Blood pressure target ≤130/80 mmHg 2
- Lifestyle modifications: smoking cessation, weight management, dietary sodium restriction
- Consider ACE inhibitor or ARB if albuminuria is present 1, 2
If Reclassified to Stage G3a (eGFR 45-59):
- Monitor every 6-12 months 3
- Nephrology referral should be discussed, especially if albuminuria ≥300 mg/g or rapid progression 3
- Medication dosing adjustments required for renally cleared drugs 9, 2
- Consider SGLT2 inhibitor if diabetes develops or albuminuria present 2, 10
Common Pitfalls to Avoid
- Do not diagnose CKD based on single eGFR measurement - requires confirmation over ≥3 months 8, 2
- Do not ignore race-free eGFR equations - older equations may overestimate kidney function in Black patients 7
- Do not skip albuminuria testing - it's essential for risk stratification and treatment decisions 2, 4
- Do not assume normal kidney function - HbA1c of 5.7% indicates prediabetes, a CKD risk factor requiring surveillance 2