ACE Inhibitors and ARBs Should Not Be Initiated When GFR is Below 30 mL/min/1.73 m²
ACE inhibitors and ARBs should not be initiated in patients with a GFR below 30 mL/min/1.73 m², though they may be continued with careful monitoring if already established on therapy and providing benefit 1, 2.
GFR Thresholds for ACE/ARB Initiation
The decision to initiate ACE inhibitors or ARBs should be guided by the following GFR thresholds:
- GFR ≥ 30 mL/min/1.73 m²: May initiate ACE inhibitors or ARBs with appropriate monitoring
- GFR < 30 mL/min/1.73 m²: Do not initiate ACE inhibitors or ARBs 1, 2
The KDIGO guidelines specifically recommend against using immunosuppressive therapy in patients with serum creatinine ≥ 3.5 mg/dL (or eGFR ≤ 30 mL/min/1.73 m²) 1. This principle extends to ACE inhibitors and ARBs due to their potential to cause further deterioration in renal function in advanced kidney disease.
Monitoring Recommendations When Using ACE/ARBs
When initiating ACE inhibitors or ARBs in patients with GFR ≥ 30 mL/min/1.73 m²:
- Check serum creatinine and potassium within 1 week of starting or increasing the dose 3
- Expect a potential increase in serum creatinine of up to 30% from baseline, which is generally acceptable 4
- Discontinue if serum creatinine rises more than 30% above baseline during the first 2 months of therapy 4
- Monitor for hyperkalemia, especially in patients with reduced GFR 2
Special Considerations
Continuing vs. Initiating Therapy
- Continuation: ACE inhibitors or ARBs may be continued in patients whose GFR declines below 30 mL/min/1.73 m² while on therapy, as long as they are tolerating the medication without significant adverse effects 5
- Initiation: New starts should be avoided when GFR is already below 30 mL/min/1.73 m² 1, 2
Temporary Discontinuation ("Sick Day Rules")
Temporarily discontinue ACE inhibitors and ARBs in patients with GFR < 60 mL/min/1.73 m² during:
- Serious intercurrent illness
- Planned IV radiocontrast administration
- Bowel preparation for colonoscopy
- Major surgery
- Situations with high risk of acute kidney injury 1, 3
Contraindications
Absolute contraindications to ACE inhibitors or ARBs include:
- Bilateral renal artery stenosis
- Previous angioedema with ACE inhibitors
- Pregnancy
- Hyperkalemia (serum potassium > 5.5 mmol/L) 2
Common Pitfalls to Avoid
- Failure to monitor renal function: Always check creatinine and potassium after initiation
- Premature discontinuation: Don't stop therapy for minor increases in creatinine (<30%)
- Combination therapy: Never use ACE inhibitors and ARBs simultaneously 1
- Ignoring hyperkalemia risk: Monitor potassium levels closely, especially in patients with reduced GFR
- Failure to temporarily discontinue during acute illness: Follow "sick day rules" to prevent acute kidney injury
Conclusion
While ACE inhibitors and ARBs provide significant cardiovascular and renoprotective benefits in many patients, the threshold for initiation should be a GFR of at least 30 mL/min/1.73 m². Below this threshold, the risks of hyperkalemia, acute kidney injury, and further deterioration of renal function generally outweigh the potential benefits when starting these medications.