Can Angiotensin Receptor Blockers (ARBs) harm the kidneys?

ARBs and Kidney Function: Potential Risks and Monitoring

ARBs can cause acute kidney injury in certain high-risk patients, but they are generally renoprotective in most patients with appropriate monitoring and careful patient selection. 1, 2

Effects of ARBs on Kidney Function

ARBs work by blocking the renin-angiotensin system (RAS), which affects kidney function in several ways:

Physiological Effects

• ARBs block the effects of angiotensin II on the kidney, causing:
  • Changes in intraglomerular hemodynamics
  • A predictable increase in serum creatinine (up to 20% is generally considered acceptable) 1
  • Reduction in intraglomerular pressure (beneficial for reducing proteinuria)

Beneficial Renal Effects

• Reduce proteinuria/albuminuria 1, 3
• Slow progression of diabetic nephropathy 1
• Provide renoprotection in chronic kidney disease 3, 4
• May increase renal blood flow through vasodilation 4

Situations Where ARBs May Harm Kidneys

ARBs can potentially harm kidneys in specific circumstances:

1. Volume-depleted patients 2

   • Patients on diuretic therapy
   • Dehydrated patients

2. Pre-existing renal insufficiency 1, 2

   • Careful monitoring required when initiating or titrating doses

3. Concomitant use with other medications 2, 5

   • NSAIDs (including COX-2 inhibitors) can cause deterioration of renal function
   • Other RAS blockers (ACE inhibitors, aliskiren) increase risk of renal dysfunction

4. Bilateral renal artery stenosis 1

   • Can cause rapid decline in renal function

5. Hypotension 1

   • Systolic blood pressure <80 mmHg can reduce renal perfusion

Monitoring Recommendations

To prevent kidney harm when using ARBs:

1. Before starting therapy:

   • Assess baseline renal function (serum creatinine, eGFR)
   • Check serum potassium
   • Evaluate volume status

2. After initiation and dose changes 1:

   • Monitor renal function and potassium within 1-2 weeks
   • Check blood pressure (including postural changes)

3. Ongoing monitoring:

   • Regular assessment of renal function
   • Monitor potassium levels, especially with concomitant use of potassium-sparing diuretics or supplements 2, 5

4. High-risk patients require closer surveillance 1:

   • Diabetes mellitus
   • Existing renal impairment
   • Low serum sodium
   • Systolic BP <80 mmHg

Risk Mitigation Strategies

1. Start with low doses and titrate gradually 1

2. Avoid combination RAS blockade 1

   • Routine combined use of an ACE inhibitor, ARB, and aldosterone antagonist is potentially harmful 1
   • Dual blockade increases risks of hypotension, hyperkalemia, and renal dysfunction 2, 5

3. Temporary discontinuation may be necessary during:

   • Acute illness with dehydration
   • Perioperative periods
   • Contrast media administration

4. Careful use with NSAIDs 2, 5

   • Monitor renal function periodically
   • Educate patients about risks of combining these medications

Special Considerations

• Diabetes: ARBs are preferred agents for patients with diabetes and albuminuria 1

• Heart Failure: Despite potential effects on renal function, ARBs improve outcomes in heart failure patients 1

• Elderly patients: Require more careful monitoring due to age-related decline in renal function 1

• Pregnancy: ARBs are contraindicated due to fetal risks 2

While ARBs can cause acute changes in kidney function, long-term studies show they are generally well-tolerated even at high doses in patients with chronic kidney disease 6, 7. The benefits of ARB therapy in protecting kidney function long-term typically outweigh the risks when used appropriately with proper monitoring.