Can Losartan (angiotensin II receptor antagonist) worsen Acute Kidney Injury (AKI)?

Losartan Can Worsen Acute Kidney Injury

Yes, losartan can worsen acute kidney injury (AKI), particularly in patients with volume depletion, preexisting renal dysfunction, or conditions that alter renal blood flow and intrarenal hemodynamics. 1, 2

Mechanism of AKI Risk with Losartan

Losartan, as an angiotensin receptor blocker (ARB), can negatively impact kidney function through several mechanisms:

• Reduces glomerular filtration pressure by blocking angiotensin II effects
• Decreases efferent arteriolar resistance, leading to reduced filtration fraction
• Alters renal blood flow, especially in patients with activated renin-angiotensin system

High-Risk Patient Populations

The risk of losartan-induced AKI is significantly higher in:

• Patients with volume or salt depletion (e.g., those on high-dose diuretics) 2
• Individuals with preexisting chronic kidney disease 1
• Patients with bilateral renal artery stenosis or stenosis in a solitary kidney 3
• Elderly patients 4
• Those with severe heart failure 5
• Patients taking other nephrotoxic medications (e.g., NSAIDs) 2

Clinical Monitoring and Management

When using losartan in patients at risk for AKI:

• Monitor renal function periodically, especially within 1-2 weeks of initiation 6, 2
• Correct volume or salt depletion prior to administration 2
• Consider withholding or discontinuing therapy in patients who develop clinically significant decreases in renal function 2
• Avoid concurrent use with other renin-angiotensin system blockers (ACE inhibitors, aliskiren) 2
• Be vigilant for increases in serum creatinine, especially in high-risk patients

Important Distinction: Acceptable vs. Concerning Creatinine Elevations

It's crucial to differentiate between acceptable and concerning creatinine elevations:

• Small elevations in serum creatinine (up to 30% from baseline) with ARBs are expected and should not be confused with AKI 1
• These modest increases do not indicate progressive kidney disease or increased mortality 1
• ARBs should not be discontinued for minor increases in serum creatinine (<30%) in the absence of volume depletion 1
• However, increases >30% or signs of AKI warrant immediate evaluation

Avoiding Common Pitfalls

1. Don't confuse expected creatinine elevation with AKI: Small increases (up to 30%) are expected and not harmful 1
2. Don't underestimate volume status: Volume depletion significantly increases AKI risk with losartan 2
3. Don't combine with other RAS blockers: Dual RAS blockade increases risk of hyperkalemia and AKI 2
4. Don't ignore risk factors: Screen for renal artery stenosis in high-risk patients before initiating therapy 3
5. Don't continue losartan during acute illness: Consider temporary discontinuation during intercurrent illness, especially with risk of volume depletion 1

While losartan has beneficial effects in chronic kidney disease management, its use requires careful monitoring and awareness of its potential to worsen acute kidney injury in susceptible patients.