Should I continue or stop losartan (50 mg daily) in a patient with impaired renal function?

Management of Losartan in a Patient with Impaired Renal Function

Losartan 50 mg daily should be continued in this patient with a creatinine of 2.2 and GFR of 47, as no dose adjustment is necessary at this level of renal impairment. 1

Rationale for Continuing Losartan

The FDA drug label for losartan specifically states that "no dose adjustment is necessary in patients with renal impairment unless a patient with renal impairment is also volume depleted" 1. This patient's GFR of 47 ml/min/1.73m² indicates moderate renal impairment, but not severe enough to warrant discontinuation of therapy.

Key considerations supporting this decision:

• Losartan has been shown to be effective and well-tolerated in patients with various degrees of renal impairment, including those with GFR between 30-60 ml/min/1.73m² 2
• Studies have demonstrated that losartan may actually retard the progression of renal insufficiency in patients with baseline elevated creatinine levels 3
• The KDOQI guidelines do not recommend routine discontinuation of RAAS antagonists in people with GFR <30 ml/min/1.73m², noting they remain nephroprotective 4

Monitoring Recommendations

While continuing losartan, implement the following monitoring protocol:

1. Short-term monitoring:

   • Check renal function and serum potassium within 1 week of continuing therapy 4
   • Reassess renal function 2-3 weeks later if stable

2. Long-term monitoring:

   • Monitor renal function and electrolytes every 3 months if stable 4
   • More frequent monitoring if clinical status changes or other medications affecting renal function are added

When to Consider Dose Reduction or Discontinuation

Consider dose reduction or temporary discontinuation in the following scenarios:

• If creatinine increases by >30% from baseline 4
• If hyperkalemia develops (K+ >5.5 mEq/L) 4
• During acute illness, especially with volume depletion
• Prior to procedures involving radiocontrast agents 4
• If the patient develops symptomatic hypotension

Clinical Pearls and Pitfalls

• Common misconception: Many clinicians unnecessarily discontinue RAAS blockers when mild-to-moderate elevations in creatinine occur, despite evidence supporting their continued benefit
• Important distinction: A small increase in creatinine (up to 30%) after starting or continuing RAAS blockers is expected and not necessarily harmful 4
• Avoid triple RAAS blockade: The combination of ACE inhibitor, ARB, and aldosterone antagonist significantly increases risk of hyperkalemia and renal dysfunction 5
• Medication interactions: NSAIDs should be avoided as they can reduce the efficacy of losartan and increase risk of renal dysfunction 4

Special Considerations

• If the patient is also on diuretics, ensure adequate volume status before continuing losartan to prevent pre-renal injury
• If potassium rises above 5.0 mEq/L, consider dietary potassium restriction before medication changes
• For patients with diabetes, losartan may provide additional renoprotective benefits beyond blood pressure control

In conclusion, the current level of renal impairment (creatinine 2.2, GFR 47) does not warrant discontinuation of losartan 50 mg daily. Close monitoring of renal function and electrolytes is essential, with dose adjustment or temporary discontinuation only if significant worsening of renal function or hyperkalemia occurs.