What is the next step in managing a patient with impaired renal function (low eGFR)?

Management of Low eGFR (Impaired Renal Function)

The next step in managing a patient with low eGFR should be a comprehensive assessment including albuminuria testing, evaluation for reversible causes of kidney dysfunction, and appropriate referrals based on eGFR severity and progression rate. 1, 2

Initial Assessment and Monitoring

Evaluate Severity and Progression

• Assess current eGFR value and compare with previous values to determine:
  • Rate of progression (rapid progression defined as >5 mL/min/1.73m² decline per year) 1
  • Severity category (G1: ≥90, G2: 60-89, G3a: 45-59, G3b: 30-44, G4: 15-29, G5: <15 mL/min/1.73m²) 1

Essential Testing

• Measure albuminuria/proteinuria (urine albumin-to-creatinine ratio) 1, 2
  • A doubling of ACR on subsequent testing exceeds laboratory variability and warrants evaluation 1
• Review medication list for nephrotoxic agents (especially NSAIDs) 2
• Assess for reversible causes of kidney dysfunction:
  • Volume depletion
  • Urinary obstruction
  • Nephrotoxic medications
  • Acute illness 2

Management Algorithm Based on eGFR Level

For eGFR 45-60 mL/min/1.73m² (CKD G3a)

1. Monitor eGFR and albuminuria at least annually 1
2. Adjust medications requiring renal dosing
3. Implement cardiovascular risk reduction:
   • Blood pressure target <130/80 mmHg 2
   • Consider statin therapy 3
   • Lifestyle modifications (sodium restriction <2g/day, regular physical activity) 2

For eGFR 30-44 mL/min/1.73m² (CKD G3b)

1. Increase monitoring frequency to every 6 months 2
2. Review and adjust medications:
   • Consider initiating ACE inhibitors or ARBs if albuminuria >300 mg/g 2
   • Monitor serum creatinine and potassium within 7-14 days after initiation 2
   • Assess metformin dosing (use with caution) 4
3. Begin monitoring for CKD complications:
   • Anemia (hemoglobin)
   • Metabolic acidosis
   • Electrolyte abnormalities 2

For eGFR <30 mL/min/1.73m² (CKD G4-G5)

1. Refer to nephrology 2, 3
2. Increase monitoring frequency to every 3 months 2
3. Medication adjustments:
   • Discontinue metformin (contraindicated with eGFR <30 mL/min/1.73m²) 4
   • Consider SGLT2 inhibitors for kidney protection if eGFR ≥20 mL/min/1.73m² 2
4. Begin discussion about renal replacement therapy options 2
5. Preserve veins suitable for potential future vascular access 2
6. Consider kidney transplant evaluation if eligible 2
7. Restrict protein intake to 0.8 g/kg/day 2

Special Considerations

Albuminuria Management

• If albuminuria present (>30 mg/g), initiate ACE inhibitors or ARBs unless contraindicated 2
• Target maximum tolerated doses with careful monitoring of potassium and creatinine 2
• Consider potassium-binding agents if hyperkalemia develops 2

Medication Management

• Review all medications for appropriate dosing in renal impairment 2
• Avoid nephrotoxic medications (NSAIDs, certain antibiotics) 2
• Temporarily discontinue ACE inhibitors/ARBs during acute illness 2
• Do not discontinue ACE inhibitors prematurely due to an initial 10-20% increase in serum creatinine 2

Imaging Considerations

• For patients requiring contrast imaging with eGFR 30-60 mL/min/1.73m²:
  • Temporarily discontinue metformin at the time of procedure
  • Re-evaluate eGFR 48 hours after imaging
  • Restart metformin if renal function is stable 4

Common Pitfalls to Avoid

1. Failing to test for albuminuria, which is essential for CKD risk stratification 1
2. Overlooking potentially reversible causes of decreased eGFR 2
3. Discontinuing ACE inhibitors/ARBs too quickly due to initial creatinine rise (up to 20% increase is acceptable) 2
4. Continuing nephrotoxic medications like NSAIDs in patients with impaired renal function 2
5. Neglecting cardiovascular risk reduction, which is essential in CKD management 2, 3
6. Delaying nephrology referral for patients with eGFR <30 mL/min/1.73m² or rapid progression 2

By following this structured approach to managing patients with low eGFR, you can help slow disease progression, prevent complications, and improve outcomes for patients with chronic kidney disease.