What steps can be taken to treat and prevent further deterioration of renal function in a patient with hypertension and impaired renal function, currently taking losartan (Angiotensin II receptor antagonist)?

Management of Hypertension and Chronic Kidney Disease

For patients with hypertension and early chronic kidney disease (CKD), angiotensin II receptor blockers (ARBs) like losartan are strongly recommended as first-line therapy to prevent further deterioration of renal function. 1

Assessment of Current Status

The patient presents with:

• 60-year-old with 4-5 year history of untreated hypertension
• Recently started on losartan
• Current labs: Creatinine 1.5 mg/dL, BUN 27 mg/dL
• Previous labs (5 years ago): Creatinine approximately 1.3 mg/dL
• Not dehydrated

This clinical picture suggests stage 3a CKD (eGFR likely between 45-59 mL/min/1.73m²), likely due to hypertensive nephropathy.

Treatment Algorithm

1. Continue and Optimize RAAS Blockade

• Maintain losartan therapy as ARBs are first-line agents for patients with hypertension and CKD 1
• Optimize losartan dosage to 100 mg daily if tolerated, as this dose provides optimal antiproteinuric effect 2
• Monitor renal function and electrolytes regularly, particularly potassium levels 3

2. Blood Pressure Control

• Target blood pressure <130/80 mmHg for patients with CKD and proteinuria 4
• If blood pressure goal not achieved with losartan alone:
  • Add a thiazide diuretic (for eGFR >30 mL/min/1.73m²) or loop diuretic (for lower eGFR) 4
  • Consider adding a calcium channel blocker as third-line agent if needed 4

3. Lifestyle Modifications

• Restrict dietary sodium to <2.0 g/day (<90 mmol/day) 4
• Implement moderate protein restriction (0.8 g/kg/day)
• Weight management if overweight/obese
• Regular physical activity appropriate to the patient's capabilities
• Smoking cessation if applicable

4. Monitoring Protocol

• Check serum creatinine and potassium within 1-2 weeks after starting or adjusting losartan dose 3
• Temporarily suspend losartan during acute illness, planned IV contrast procedures, or prior to major surgery 1
• Regular monitoring of blood pressure, renal function, and proteinuria every 3-6 months

Important Considerations and Potential Pitfalls

1. Hyperkalemia risk: Monitor potassium levels closely, especially if adding other medications that may increase potassium (e.g., potassium-sparing diuretics) 3

2. Acute kidney injury risk: Losartan may cause acute kidney injury in patients with bilateral renal artery stenosis, severe heart failure, or volume depletion 3. Consider renal artery imaging if there's suspicion of renal artery stenosis.

3. Medication interactions: NSAIDs can reduce the efficacy of ARBs and increase risk of renal dysfunction 3. Advise patient to avoid or minimize NSAID use.

4. Avoid dual RAAS blockade: Do not combine losartan with ACE inhibitors or direct renin inhibitors as this increases adverse effects without additional benefit 3

5. Temporary medication adjustments: Instruct the patient to hold losartan during episodes of diarrhea, vomiting, or other conditions that may cause volume depletion 1

By implementing this comprehensive management approach, you can help prevent further deterioration of renal function in this patient with hypertension and early CKD. Regular monitoring and appropriate adjustments to therapy based on the patient's response will be essential for long-term kidney protection.