Should I change the medication regimen from Enalapril and HCTZ for hypertension given the patient's impaired renal function?

Management of Hypertension in a Patient with Impaired Renal Function

Based on the laboratory findings showing impaired renal function (eGFR 52 mL/min/1.73m², elevated creatinine 1.40 mg/dL, and BUN 26 mg/dL), the current regimen of enalapril and HCTZ should be modified to optimize treatment while protecting kidney function.

Assessment of Current Status

• The patient has stage 3a chronic kidney disease (CKD) with an eGFR of 52 mL/min/1.73m² 1
• Current medications include enalapril (an ACE inhibitor) and hydrochlorothiazide (HCTZ, a thiazide diuretic) for hypertension management 2
• Elevated creatinine (1.40 mg/dL) and BUN (26 mg/dL) indicate impaired renal function that requires medication adjustment 2
• Other laboratory values are within normal range, including electrolytes (sodium, potassium, chloride, calcium) and liver function tests 1

Recommended Medication Adjustments

• Continue enalapril but adjust the dosage based on renal function. For patients with eGFR between 30-80 mL/min, a starting dose of 5 mg daily is recommended with careful titration 2
• Consider reducing the HCTZ dose to a very low dose (6-12.5 mg) which can still provide synergistic antihypertensive effects with enalapril while minimizing adverse metabolic effects 3
• Monitor renal function and electrolytes (particularly potassium) within 1-2 weeks of any medication adjustment 4

Rationale for Continuing ACE Inhibitor

• ACE inhibitors like enalapril have been shown to be superior to non-ACE containing regimens for preventing end-stage kidney disease in patients with CKD, with a 30% risk reduction 1
• ACE inhibitors provide both systemic blood pressure lowering and reduction in intraglomerular pressure, which is beneficial for kidney protection 1
• A transient increase in creatinine after starting ACE inhibitors is expected and not necessarily a reason to discontinue therapy unless the increase is significant (>30%) 1

Monitoring Recommendations

• Check serum creatinine, BUN, and electrolytes (especially potassium) within 1-2 weeks after medication adjustment 4
• Monitor for signs of worsening renal function or hyperkalemia, which would necessitate further dose adjustment 2
• If blood pressure remains uncontrolled despite optimized doses, consider adding a calcium channel blocker rather than increasing diuretic dose 1

Important Precautions

• Avoid potassium-sparing diuretics in this patient with impaired renal function due to increased risk of hyperkalemia 1, 4
• If the patient develops significant worsening of renal function (increase in creatinine >30%) or hyperkalemia (K+ >5.0 mEq/L), consider further reducing the ACE inhibitor dose or switching to an alternative agent 2
• Advise the patient to avoid nonsteroidal anti-inflammatory drugs (NSAIDs) as they can worsen renal function and reduce the effectiveness of the antihypertensive regimen 1
• Ensure adequate hydration and caution the patient about excessive perspiration, vomiting, or diarrhea which may lead to volume depletion and further impair renal function 2

Long-term Management Strategy

• Target blood pressure should be individualized, but generally aim for <130/80 mmHg in patients with CKD 1
• Regular monitoring of renal function and electrolytes every 3-6 months is recommended for stable patients 4
• Consider additional cardiovascular risk factor management including lipid control and lifestyle modifications 1

This approach balances the benefits of continuing renin-angiotensin system blockade for kidney protection while minimizing the risks associated with these medications in the setting of impaired renal function.