Stage 3a Chronic Kidney Disease
A GFR of 58 mL/min/1.73 m² corresponds to Stage 3a chronic kidney disease, defined as moderately decreased kidney function with GFR between 45-59 mL/min/1.73 m². 1, 2
Understanding the Classification
The KDIGO classification system subdivides Stage 3 CKD into two distinct categories because mortality and adverse outcome risks differ substantially between these subgroups 1, 2:
- Stage 3a: GFR 45-59 mL/min/1.73 m² (your patient falls here)
- Stage 3b: GFR 30-44 mL/min/1.73 m²
This subdivision is clinically important because Stage 3b patients demonstrate significantly higher risks of progression to kidney failure and cardiovascular events compared to Stage 3a patients 1, 3.
Critical Diagnostic Requirement
A single GFR measurement of 58 does not establish chronic kidney disease. The diagnosis requires abnormalities to be present for >3 months to distinguish CKD from acute kidney injury 1, 2, 4. You must either:
- Review historical eGFR measurements showing persistent reduction, OR
- Repeat serum creatinine and eGFR measurement after 3 months to confirm chronicity 4
Essential Next Step: Measure Albuminuria
Immediately measure urine albumin-to-creatinine ratio (UACR) on a random spot urine sample 1, 2, 4. The combination of GFR and albuminuria determines:
- Risk stratification for progression and cardiovascular events 1, 4
- Treatment intensity and monitoring frequency 2
- Need for nephrology referral 2
Albuminuria categories are 1, 4:
- A1: <30 mg/g (normal to mildly increased)
- A2: 30-300 mg/g (moderately increased)
- A3: >300 mg/g (severely increased)
Immediate Clinical Actions
Medication Review
Review and adjust all renally-cleared medications at this GFR level, as drug accumulation can occur with reduced kidney function 2.
Blood Pressure Management
- Target BP ≤140/90 mmHg if UACR <30 mg/g 2
- Target BP <130/80 mmHg if any degree of albuminuria is present 2
- Initiate ACE inhibitor or ARB if the patient has diabetes with hypertension and any degree of albuminuria 2
Cardiovascular Risk Reduction
Patients with Stage 3a CKD face a 2- to 4-fold increased cardiovascular risk compared to those without CKD 2. Address all modifiable cardiovascular risk factors aggressively.
Lifestyle Modifications
Implement sodium restriction, regular physical activity, smoking cessation, and weight management 2.
Monitoring Strategy
For Stage 3a with normal albuminuria (A1): Monitor eGFR and UACR annually 2
For Stage 3a with moderately increased albuminuria (A2): Monitor 2-3 times yearly 2
For Stage 3a with severely increased albuminuria (A3): Monitor 3-4 times yearly and refer to nephrology 2
Nephrology Referral Indications
Nephrology referral is NOT necessary for Stage 3a CKD with normal albuminuria and stable function 2. However, refer if 2:
- Severely increased albuminuria (≥300 mg/g) is present
- Rapid decline in eGFR occurs
- Uncertainty about the underlying cause exists
- Difficulty managing CKD complications arises
Common Pitfall to Avoid
Do not rely on serum creatinine alone. Serum creatinine underestimates CKD in 80.6% of older adults with Stage 3 disease who have creatinine values ≤1.5 mg/dl 5. Always calculate eGFR using validated equations (CKD-EPI 2021) 2, 4.