A 48-year-old woman with hypertension and chronic kidney disease (eGFR 35 mL/min/1.73 m²) presents for antihypertensive management. She has no diabetes. Which agent is the preferred first-line choice to slow the progression of renal disease?

Explanation

## First-Line Antihypertensive in CKD Without Diabetes **Key Point:** ARBs (angiotensin II receptor blockers) or ACE inhibitors are first-line agents for hypertension in chronic kidney disease because they reduce glomerular hyperfiltration and slow progression to end-stage renal disease [cite:KD Tripathi 8e Ch 12]. ### Mechanism of Renal Protection in CKD 1. **Efferent Arteriole Dilation:** ARBs block AT1 receptors, causing preferential dilation of the efferent arteriole. 2. **Reduced Intraglomerular Pressure:** This decreases glomerular capillary hydrostatic pressure, reducing proteinuria and slowing glomerulosclerosis. 3. **Anti-inflammatory & Anti-fibrotic:** ARBs reduce TGF-β signaling, limiting renal fibrosis and tubular atrophy. 4. **Evidence:** Multiple RCTs (IDNT, RENAAL) demonstrate that ARBs slow CKD progression independent of blood pressure lowering. ### Why Losartan (ARB) Over ACE-I in This Context Both ARBs and ACE-I are equivalent for renal protection. Losartan is listed here as the representative ARB; either class is acceptable. The choice between ARB and ACE-I depends on: - **ACE-I:** Preferred if cough is not an issue; slightly more data in CKD. - **ARB:** Preferred if ACE-I causes cough; equally effective for renal protection. **High-Yield:** ARBs/ACE-Is are the ONLY class proven to slow CKD progression independent of systemic blood pressure reduction. ### Comparison with Other Agents in CKD | Agent | Effect on GFR | Effect on Proteinuria | Renal Outcome | |-------|---------------|-----------------------|----------------| | **ARB/ACE-I** | Reduces hyperfiltration | Reduces proteinuria | Slows CKD progression | | **Beta-Blocker** | Minimal renal effect | No reduction | No CKD benefit | | **Calcium Channel Blocker** | Afferent dilation | Minimal reduction | No CKD benefit | | **Loop Diuretic** | Variable | No reduction | No CKD benefit | **Clinical Pearl:** In CKD, target BP is <120 mmHg systolic (SPRINT trial). An ARB/ACE-I should be the backbone of any regimen, with additional agents (e.g., calcium channel blocker, thiazide-like diuretic) added as needed. **Warning:** Monitor serum potassium and creatinine 1–2 weeks after initiation or dose increase; expect a small rise in creatinine (10–20%) due to reduced hyperfiltration—this is NOT progression and should not prompt discontinuation.