A 58-year-old man with chronic kidney disease (eGFR 35 mL/min/1.73m²) and hypertension presents with ankle edema and dyspnea on exertion. His current medications include lisinopril and amlodipine. On examination, BP is 158/92 mmHg, JVP elevated at 8 cm, and bilateral ankle edema present. Serum K⁺ is 5.8 mEq/L, Na⁺ 138 mEq/L, and creatinine 2.1 mg/dL. Which diuretic would be most appropriate to initiate for volume overload management in this patient?

## Clinical Scenario Analysis This patient has **CKD stage 3b with volume overload** (edema, dyspnea, elevated JVP) and **hyperkalemia** (K⁺ 5.8 mEq/L). He is already on an ACE inhibitor (lisinopril), which further raises potassium risk. ## Why Furosemide Is Correct **Key Point:** Loop diuretics (furosemide) are the agents of choice for volume overload in moderate-to-advanced CKD because they: 1. Remain effective even at low GFR (eGFR 35) 2. Actively secrete into the tubular lumen via organic acid transporters 3. Cause **kaliuresis** — they increase urinary potassium excretion, helping to lower the dangerously elevated K⁺ 4. Are not contraindicated by reduced renal function **High-Yield:** Loop diuretics are the **first-line agents for edema and dyspnea in CKD patients**, especially those with eGFR < 45 mL/min/1.73m². **Clinical Pearl:** The combination of ACE inhibitor + hyperkalemia + volume overload makes furosemide ideal because it addresses both the volume problem AND lowers serum potassium simultaneously. ## Why Other Options Are Wrong | Diuretic | Problem in This Patient | |---|---| | **Spironolactone** | K⁺-sparing agent; would **worsen hyperkalemia** in a patient already on ACE inhibitor with K⁺ 5.8 mEq/L. Contraindicated. | | **Hydrochlorothiazide** | Thiazides are **ineffective in CKD** (eGFR < 45); require adequate GFR for tubular secretion and action. Also causes hyperkalemia risk reduction but less effective than loop diuretics in advanced CKD. | | **Acetazolamide** | Carbonic anhydrase inhibitor; used for metabolic alkalosis or acute mountain sickness, not volume overload. Causes hyperkalemia and metabolic acidosis — wrong agent for this scenario. | ## Diuretic Efficacy by GFR ```mermaid flowchart TD A[CKD Patient with Volume Overload]:::outcome --> B{eGFR Level?}:::decision B -->|eGFR > 45| C[Thiazides effective]:::action B -->|eGFR 30-45| D[Loop diuretics preferred]:::action B -->|eGFR < 30| E[Loop diuretics only]:::urgent C --> F[Hydrochlorothiazide, Chlorthalidone] D --> G[Furosemide, Torsemide] E --> H[High-dose Furosemide] G --> I[Also lowers K⁺]:::outcome H --> J[Also lowers K⁺]:::outcome ``` [cite:KD Tripathi 8e Ch 42]